android解析json数据

2021-12-18 05:39:40

本文讲解android解析json数据。客户端接收服务端发来的4种json数据，分别解析成四种类型Person , List<Person> , List<String> , List<Map<String,Object>>，从MainActivity传递到OtherActivity.

接收的服务器端的4种json数据分别为：

1. {"person":{"address":"香港","id":1001,"name":"刘德华"}}

2. {"persons":[{"address":"香港","id":1001,"name":"刘德华"},{"address":"韩国","id":1001,"name":"宋慧乔"}]}

3. {"listString":["美国","中国","俄罗斯"]}

4. {"listMap":[{"id":1001,"address":"香港","name":"刘德华"},{"id":1002,"address":"韩国","name":"宋慧乔"}]}

客户端相应4种操作：

1. MainActivity 将json数据解析成Person类，用Intent将Peson对象传递给OtherActvity. 设置标记click_flag = person

2. MainActivity 将json数据解析成List<Person>，用Intent将List<Person>传递给OtherActvity. 设置标记click_flag = persons

3. MainActivity 将json数据解析成List<String>，用Intent将List<String>传递给OtherActvity. 设置标记click_flag = listString

4. MainActivity 将json数据解析成List<Map<String,Object>>，用Intent将List<Map<String,Object>>传递给OtherActvity. 设置标记click_flag = listMap

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三点重点注意点：

1. 在AndroidManifest.xml中加上

<uses-permission android:name="android.permission.INTERNET" />

2. android中Http访问时 connection.getResponseCode()不被执行。添加访问网络的授权后，仍不能执行

3. 在android的两个activity中，如何用Intent传递Person对象，List<Person>,List<Map<String,Object>>类型。

一.Intent 传递 Person对象

传递 intent.putExtra("person", (Serializable)person);

接收 Person person =(Person) intent.getSerializableExtra("person");

二.Intent 传递 List<Person>对象

传递 intent.putExtra("persons", (Serializable) list);

接收 List<Person> list = (List<Person>) intent.getSerializableExtra("persons");

三. Intent传递 List<Map<String,Object>>类型

传递 intent.putExtra("listMap", (Serializable) list);

接收 List<Map<String, Object>> list = (List<Map<String, Object>>) intent.getSerializableExtra("listMap");

注意：Intent 传递的对象object必须都实现Serializable接口，List<Object>内的object也必须要实现Serializable接口.

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1.点击“解析person数据”，反馈结果如下：

2. 点击“解析persons数据”，反馈结果如下：

3. 点击“解析listString数据”，反馈结果如下：

4.点击“解析listMap数据”，反馈结果如下：

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程序思路：

1.服务器端产生4种类型的json数据，客户端android用GET方式分别获取服务器端返回的json数据，http 请求传递参数action_flag. 服务器端根据action_flag 返回不同的json数据给客户端。

2.客户端将4种不同的json数据解析成4中不同的结果类型(Person,List<Person>,List<String>,List<Map<String,Object>>)，用Intent方式由MainActivity传递给OtherActivity,在OtherActvity中显示解析的结果。

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客户端android工程目录(左)和服务器端web工程目录(右)

1. AndroidManifest.xml 加上网络访问权限

<uses-permission android:name="android.permission.INTERNET" />

2.activity_main.xml 主机面

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	xmlns:tools="http://schemas.android.com/tools"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:orientation="vertical">"
	<Button
		android:id="@+id/person"
		android:layout_width="match_parent"
		android:layout_height="wrap_content"
		android:text="解析Person数据" />
	<Button
		android:id="@+id/persons"
		android:layout_width="match_parent"
		android:layout_height="wrap_content"
		android:text="解析Persons数据" />
	<Button
		android:id="@+id/listString"
		android:layout_width="match_parent"
		android:layout_height="wrap_content"
		android:text="解析listString数据" />
	<Button
		android:id="@+id/listMap"
		android:layout_width="match_parent"
		android:layout_height="wrap_content"
		android:text="解析listMap数据" />
</LinearLayout>

3. avtivity_other.xml 点击主界面的按钮后相应的界面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:orientation="vertical" >
	
	<TextView 
		android:id="@+id/msg"
		android:layout_width="match_parent"
		android:layout_height="wrap_content"		
		
		/>
	
</LinearLayout>

4.MainActivity.java

package com.android.myjson;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import com.json.data.Person;
import com.json.http.HttpUtils;
import com.json.tools.JsonTools;

import android.os.Bundle;
import android.os.StrictMode;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity implements OnClickListener {

	private Button person, persons, listString, listMap;
	private static final String TAG = "MainActivity";

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		closeStrictMode();

		person = (Button) findViewById(R.id.person);

		persons = (Button) findViewById(R.id.persons);
		listString = (Button) findViewById(R.id.listString);
		listMap = (Button) findViewById(R.id.listMap);

		person.setOnClickListener(this);
		persons.setOnClickListener(this);
		listString.setOnClickListener(this);
		listMap.setOnClickListener(this);

	}

	@Override
	public void onClick(View v) {
		String url_path = "";
		String jsonString = "";
		switch (v.getId()) {
		case R.id.person:
			url_path = "http://192.168.0.102:8080/json_Project/servlet/JsonAction?action_flag=person";
			jsonString = HttpUtils.getJsonContent(url_path, "utf-8");
			Person person = JsonTools.getPerson("person", jsonString);
			
			Intent intent = new Intent(MainActivity.this, OtherActivity.class);
			intent.putExtra("click_flag", "person"); // 标记当前intent是按钮 person
			intent.putExtra("person", (Serializable)person);
			startActivity(intent);

			break;
		case R.id.persons:
			url_path = "http://192.168.0.102:8080/json_Project/servlet/JsonAction?action_flag=persons";
			jsonString = HttpUtils.getJsonContent(url_path, "utf-8");
			try {

				List<Person> list = JsonTools.getPersons("persons", jsonString);
				Intent intent2 = new Intent(MainActivity.this,
						OtherActivity.class);
				intent2.putExtra("click_flag", "persons"); // 标记当前intent按钮是persons
															
				intent2.putExtra("persons", (Serializable) list);
				startActivity(intent2);

			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			break;
		case R.id.listString:
			url_path = "http://192.168.0.102:8080/json_Project/servlet/JsonAction?action_flag=listString";
			jsonString = HttpUtils.getJsonContent(url_path, "utf-8");
			List<String> list = new ArrayList<String>();
			try {
				list = (ArrayList<String>) JsonTools.getListString(
						"listString", jsonString);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			Intent intent2 = new Intent(this, OtherActivity.class);
			intent2.putExtra("click_flag", "listString"); // 标记
															// 当前intent按钮是listString
			intent2.putStringArrayListExtra("listString",
					(ArrayList<String>) list); // 参数中的list要加强制转换
			startActivity(intent2);
			break;
		case R.id.listMap:
			url_path = "http://192.168.0.102:8080/json_Project/servlet/JsonAction?action_flag=listMap";
			jsonString = HttpUtils.getJsonContent(url_path, "utf-8");
			List<Map<String, Object>> list2 = new ArrayList<Map<String, Object>>();
			try {
				list2 = JsonTools.getListMap("listMap", jsonString);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

			Intent intent3 = new Intent(MainActivity.this, OtherActivity.class);
			intent3.putExtra("click_flag", "listMap"); // 标记 当前intent按钮是listMap
			// 用Intent传递List<Map<String,Object>> 对象，其中HashMap实现了Serializable
			intent3.putExtra("listMap", (Serializable) list2);
			startActivity(intent3);
			break;
		}

	}

	@SuppressLint("NewApi")
	public static void closeStrictMode() {
		StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
				.detectAll().penaltyLog().build());
	}

}

5.OtherActivity.java

package com.android.myjson;

import java.util.List;
import java.util.Map;

import com.json.data.Person;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

public class OtherActivity extends Activity {

	private TextView textView;

	public OtherActivity() {
		// TODO Auto-generated constructor stub
	}

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_other);

		textView = (TextView) findViewById(R.id.msg);

		Intent intent = getIntent();
		String click_flag = intent.getStringExtra("click_flag");
		if ("person".equals(click_flag)) { // 如果是点击 person按钮
			// 接收Intent传递的Person对象
			Person person =(Person) intent.getSerializableExtra("person");  
			textView.setText(person.toString());
		} else if ("persons".equals(click_flag)) {// 如果是点击 persons按钮
			
			// 接收Intent传递的List<Person>参数
			@SuppressWarnings("unchecked")
			List<Person> list = (List<Person>) intent
					.getSerializableExtra("persons");
			String persons = "";
			for (Person person : list) {
				persons += person.toString() + "\n";
			}
			textView.setText(persons);
		} else if ("listString".equals(click_flag)) {
			List<String> list = (List<String>) intent
					.getStringArrayListExtra("listString");

			String listString = "";
			for (String s : list) {
				listString += s + "\n";
			}
			textView.setText(listString);
		} else if ("listMap".equals(click_flag)) {
			//接收Intent传递的List<Map<String,Object>>参数
			@SuppressWarnings("unchecked")
			List<Map<String, Object>> list = (List<Map<String, Object>>) intent
					.getSerializableExtra("listMap");

			String listMapString = "";
			for (Map<String, Object> map : list) {
				// 遍历一个Map
				for (Map.Entry<String, Object> entry : map.entrySet()) {
					String key = entry.getKey();
					Object value = entry.getValue();
					listMapString += " " + key + " : " + value + " ";
				}
				listMapString += "\n";
			}

			textView.setText(listMapString);
		}

	}
}

6.Person.java

package com.json.data;

import java.io.Serializable;

public class Person implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private int id;
	private String name;
    private String address;
	
	public Person() {
		// TODO Auto-generated constructor stub
	}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public Person(int id, String name, String address) {
		super();
		this.id = id;
		this.name = name;
		this.address = address;
	}

	@Override
	public String toString() {
		return "Person [id=" + id + ", name=" + name + ", address=" + address
				+ "]";
	}
	

}

7.HttpUtils.java

package com.json.http;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import android.annotation.SuppressLint;
import android.os.StrictMode;


public class HttpUtils {

	public HttpUtils() {
		// TODO Auto-generated constructor stub
	}
	
	public static String getJsonContent(String url_path ,String encode){
		
		String jsonString = "";
		try {
			URL url = new URL(url_path);			
			HttpURLConnection connection = (HttpURLConnection)url.openConnection();
			
			connection.setConnectTimeout(3000);
			connection.setRequestMethod("GET");
			connection.setDoInput(true);  //从服务器获得数据
			
			int responseCode = connection.getResponseCode();			
			
			if (200 == responseCode) {
				jsonString = changeInputStream(connection.getInputStream(),encode);
				
			}
			
		
			
		} catch (Exception e) {
			// TODO: handle exception
		}
		
	//
		return jsonString;
	}

	private static String changeInputStream(InputStream inputStream , String encode) throws IOException {
		// TODO Auto-generated method stub
		String  jsonString = null;
		
		ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
		byte[] data = new byte[1024];
		int len = 0;
		while((len=inputStream.read(data))!=-1){
			outputStream.write(data, 0, len);
		}
		
		jsonString = new String(outputStream.toByteArray(), encode);

		inputStream.close();
		
		
		return jsonString;
	}
	
}

8.JsonTools.java

package com.json.tools;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.json.data.Person;

/**
 * 完成对json数据的解析
 * 
 * @author ben
 * 
 */
public class JsonTools {

	private static final String TAG = "JsonTools";

	public JsonTools() {
		// TODO Auto-generated constructor stub
	}

	public static Person getPerson(String key, String jsonString) {
		Person person = new Person();
		try {
			// jsonObject ={"person":{"address":"香港","id":1001,"name":"刘德华"}}
			JSONObject jsonObject = new JSONObject(jsonString);
			// personObject = {"address":"香港","id":1001,"name":"刘德华"}
			JSONObject personObject = jsonObject.getJSONObject(key); // 此处key = "person"
			person.setId(personObject.getInt("id"));
			person.setName(personObject.getString("name"));
			person.setAddress(personObject.getString("address"));

		} catch (Exception e) {
			// TODO: handle exception
		}

		return person;

	}
	
	public static List<Person> getPersons(String key , String jsonString) throws Exception{
		List<Person> list = new ArrayList<Person>();
		//jsonObject={"persons":[{"address":"香港","id":1001,"name":"刘德华"},{"address":"韩国","id":1002,"name":"宋慧乔"}]} 
		JSONObject jsonObject = new JSONObject(jsonString);
		//jsonArray =[{"address":"香港","id":1001,"name":"刘德华"},{"address":"韩国","id":1002,"name":"宋慧乔"}]
		JSONArray jsonArray = jsonObject.getJSONArray(key);   //此处key = persons,取得
		for (int i = 0; i < jsonArray.length(); i++) {
			JSONObject personObject = jsonArray.getJSONObject(i);
			Person person = new Person();
			person.setId(personObject.getInt("id"));
			person.setName(personObject.getString("name"));  
			person.setAddress(personObject.getString("address"));
			list.add(person);			
		}
		
		
		return list;
	}
	public static List<String> getListString(String key,String jsonString) throws Exception{
		List<String> list = new ArrayList<String>();
		// jsonObject = {"listString":["美国","中国","俄罗斯"]}
		JSONObject jsonObject = new JSONObject(jsonString);
		// jsonArray = ["美国","中国","俄罗斯"]
		JSONArray jsonArray = jsonObject.getJSONArray(key);
		
		for (int i =0 ; i<jsonArray.length();i++) {
		
			String s = jsonArray.getString(i);
			list.add(s);
		}
		
		return list;
	}
	
	
	public static List<Map<String, Object>> getListMap(String key , String jsonString) throws Exception{
		List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();
		
		JSONObject jsonObject = new JSONObject(jsonString);
		JSONArray jsonArray = jsonObject.getJSONArray(key);
		for (int i = 0; i < jsonArray.length(); i++) {			
			JSONObject jsonObject2 = jsonArray.getJSONObject(i);
			Map<String, Object> map = new HashMap<String, Object>();
			//重点：如何遍历json 对象中的key			
			Iterator<String> iterator = jsonObject2.keys(); // 获取json对象中的key，返回一个string集合。
			while(iterator.hasNext()){
				String json_key = iterator.next();
				Object json_value = jsonObject2.get(json_key);
				if (json_value == null) { //因为JSON value可为 null;
					json_value = "";
				}
				map.put(json_key, json_value);
			}
			list.add(map);
		}
		
		
		return list;
	}
    
}

服务器端 json_Project

1.JsonAction.java

package com.json.action;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.json.service.JsonService;
import com.json.tools.JsonTools;

public class JsonAction extends HttpServlet {

	JsonService jsonService ;
	/**
	 * Constructor of the object.
	 */
	public JsonAction() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doPost(request, response);
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		PrintWriter out = response.getWriter();
		// 获取 person的 list , 保存为json数据
	//	String jsonString = JsonTools.creatJsonString("persons", jsonService.getListPersons());
		
		String jsonString ="";
		String action_flag = request.getParameter("action_flag");
		if ("person".equals(action_flag)) {
			jsonString = JsonTools.creatJsonString("person", jsonService.getPerson());
		} else if("persons".equals(action_flag)) {
			jsonString = JsonTools.creatJsonString("persons", jsonService.getListPersons());
		}else if("listString".equals(action_flag)) {
			jsonString = JsonTools.creatJsonString("listString", jsonService.getListString());
		}else if("listMap".equals(action_flag)) {
			jsonString = JsonTools.creatJsonString("listMap", jsonService.getListMap());
		}
		
		out.println(jsonString);
		System.out.println("jsonString"+jsonString);
		
		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
		jsonService = new JsonService();
	}

}

2.Person.java

package com.json.data;

public class Person {
	private int id;
	private String name;
    private String address;
	
	public Person() {
		// TODO Auto-generated constructor stub
	}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public Person(int id, String name, String address) {
		super();
		this.id = id;
		this.name = name;
		this.address = address;
	}

	@Override
	public String toString() {
		return "Person [id=" + id + ", name=" + name + ", address=" + address
				+ "]";
	}
	

}

3.JsonService.java

package com.json.service;

import java.util.ArrayList;
import java.util.Map;
import java.util.HashMap;
import java.util.List;



import com.json.data.Person;

public class JsonService {

	public JsonService() {
		// TODO Auto-generated constructor stub
	}

	public static Person getPerson() {

		Person person = new Person(1001, "刘德华", "香港");
		return person;

	}

	public static List<Person> getListPersons() {
		List<Person> persons = new ArrayList<Person>();
		Person person1 = new Person(1001, "刘德华", "香港");
		Person person2 = new Person(1002, "宋慧乔", "韩国");
		persons.add(person1);
		persons.add(person2);
		return persons;

	}
	
	public static List<String> getListString(){
		
		List<String> list = new ArrayList<String>();
		list.add("美国");
		list.add("中国");
		list.add("俄罗斯");	
		
		return list;
	} 

	
	public static List<java.util.Map<String, Object>> getListMap(){
		List<java.util.Map<String, Object>> list = new ArrayList<Map<String,Object>>();
		java.util.Map<String,Object> map1 = new HashMap<String,Object>();
		map1.put("id",1001);
		map1.put("name","刘德华");
		map1.put("address","香港");
		
		java.util.Map<String,Object> map2 = new HashMap<String,Object>();
		map2.put("id",1002);
		map2.put("name","宋慧乔");
		map2.put("address","韩国");
		
		list.add(map1);
		list.add(map2);
		
		return list;
		
	}
}

4.TestJson.java

package com.json.test;

import com.json.service.JsonService;
import com.json.tools.JsonTools;

public class TestJson {

	public TestJson() {
		// TODO Auto-generated constructor stub
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		//Test1 Person 	
		System.out.println("Json数据格式测试结果：\n");
		String jsonString1 = JsonTools.creatJsonString("person", JsonService.getPerson());
		//Test2 persons
		String jsonString2 = JsonTools.creatJsonString("persons", JsonService.getListPersons());
		//Test3 listString
		String jsonString3 = JsonTools.creatJsonString("listString",JsonService.getListString());
		//Test 4 listMap
		String jsonString4 = JsonTools.creatJsonString("listMap",JsonService.getListMap());
		
		System.out.println("测试结果1："+jsonString1+"\n");
		System.out.println("测试结果2："+jsonString2+"\n");
		System.out.println("测试结果3："+jsonString3+"\n");
		System.out.println("测试结果4："+jsonString4);

	}

}

5.JsonTools.java

package com.json.tools;

import net.sf.json.JSONObject;

public class JsonTools {

	/**
	 * @param key 	表示json字符串的头信息
	 * @param value 表示解析几何的类型
	 * @return
	 */
	public static String creatJsonString(String key, Object value) {

		JSONObject jsonObject = new JSONObject();
		jsonObject.put(key, value);
		return jsonObject.toString();
	}

}

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