这一篇博客是对上一篇《JAVA网络编程之获取网络资源》的扩充，这一篇将使用HttpURLConnection来模拟一个表单的提交。在B/S架构的系统中，请求时通过浏览器与服务端进行交互的，提交请求参数时使用form表单进行提交，但是有很多时候，我们需要在程序中直接调用HTTP接口，同时需要传递一些参数，那么这个时候我们就可以通过使用HttpURLConnection来模拟表单的提交过程。
首先，我们可以对请求进行封装
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
/**
* 请求
*
* @author jianggujin
*
*/
public class HttpRequest
{
/** 请求地址 **/
private String url = null;
/** 请求方法 **/
private RequestMethod method = RequestMethod.GET;
/** 编码 **/
private String charset = "UTF-8";
/** 请求头信息 **/
private Map<String, String> headers = new HashMap<String, String>();
/** 请求参数 **/
private Map<String, List<String>> params = new HashMap<String, List<String>>();
/**
* 默认构造方法
*/
public HttpRequest()
{
}
/**
* 构造方法
*
* @param url
*/
public HttpRequest(String url)
{
this.url = url;
}
/**
* 构造方法
*
* @param url
* @param method
*/
public HttpRequest(String url, RequestMethod method)
{
this.url = url;
this.method = method;
}
/**
* 获得请求地址
*
* @return
*/
public String getUrl()
{
return url;
}
/**
* 设置请求地址
*
* @param url
*/
public void setUrl(String url)
{
this.url = url;
}
/**
* 获得请求方法
*
* @return
*/
public RequestMethod getMethod()
{
return method;
}
/**
* 设置请求方法
*
* @param method
*/
public void setMethod(RequestMethod method)
{
this.method = method;
}
/**
* 获得编码
*
* @return
*/
public String getCharset()
{
return charset;
}
/**
* 设置编码
*
* @param charset
*/
public void setCharset(String charset)
{
this.charset = charset;
}
/**
* 添加头信息
*
* @param name
* @param value
*/
public void addHeader(String name, String value)
{
headers.put(name, value);
}
/**
* 添加请求参数
*
* @param name
* @param value
*/
public void addParam(String name, String value)
{
List<String> list = params.get(name);
if (list == null)
{
list = new ArrayList<String>();
params.put(name, list);
}
list.add(value);
}
/**
* 设置请求参数
*
* @param name
* @param value
*/
public void setParam(String name, String value)
{
List<String> list = params.get(name);
if (list == null)
{
list = new ArrayList<String>();
params.put(name, list);
}
else
{
// 清空已有参数
list.clear();
}
list.add(value);
}
/**
* 获得请求头迭代器
*
* @return
*/
public Iterator<Entry<String, String>> getHeaders()
{
return headers.entrySet().iterator();
}
/**
* 获得请求参数迭代器
*
* @return
*/
public Iterator<Entry<String, List<String>>> getParams()
{
return params.entrySet().iterator();
}
}
/**
* 请求方法
*
* @author jianggujin
*
*/
enum RequestMethod
{
GET, POST
}在HttpRequest类中，包含了一个请求的基本信息，然后我们再封装一个类用于HTTP的请求。
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
/**
* Http请求客户端
*
* @author jianggujin
*
*/
public abstract class HttpClient
{
/** 连接超时时间 **/
private int connectTimeOut = 10 * 1000;
/** 读超时时间 **/
private int readTimeOut = 10 * 1000;
/**
* 获得连接超时时间
*
* @return
*/
public int getConnectTimeOut()
{
return connectTimeOut;
}
/**
* 设置连接超时发时间
*
* @param connectTimeOut
*/
public void setConnectTimeOut(int connectTimeOut)
{
this.connectTimeOut = connectTimeOut;
}
/**
* 获得读超时时间
*
* @return
*/
public int getReadTimeOut()
{
return readTimeOut;
}
/**
* 设置读超时时间
*
* @param readTimeOut
*/
public void setReadTimeOut(int readTimeOut)
{
this.readTimeOut = readTimeOut;
}
/**
* 执行
*/
public void execute(HttpRequest request) throws IOException
{
String url = request.getUrl();
// GET方式请求
if (request.getMethod() == RequestMethod.GET)
{
// 拼接参数
if (url.indexOf('?') != -1)
{
if (url.endsWith("?"))
{
url += dealParam(request);
}
else
{
if (url.endsWith("&"))
{
url += dealParam(request);
}
else
{
url += ("&" + dealParam(request));
}
}
}
else
{
url += ("?" + dealParam(request));
}
}
// 获得Http连接
HttpURLConnection connection = (HttpURLConnection) new URL(url)
.openConnection();
// 设置超时时间
connection.setConnectTimeout(connectTimeOut);
connection.setReadTimeout(readTimeOut);
// 设置请求头
Iterator<Entry<String, String>> headers = request.getHeaders();
while (headers.hasNext())
{
Entry<String, String> entry = headers.next();
connection.setRequestProperty(entry.getKey(), entry.getValue());
}
connection.setUseCaches(false);
// 如果是POST请求
if (request.getMethod() == RequestMethod.POST)
{
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setRequestMethod("POST");
}
connection.connect();
// 如果是POST请求
if (request.getMethod() == RequestMethod.POST)
{
OutputStreamWriter writer = new OutputStreamWriter(
connection.getOutputStream(), request.getCharset());
writer.write(dealParam(request));
writer.flush();
writer.close();
}
if (connection.getResponseCode() == HttpURLConnection.HTTP_OK)
{
onSuccess(HttpURLConnection.HTTP_OK, connection.getInputStream());
}
else
{
onSuccess(connection.getResponseCode(), connection.getErrorStream());
}
connection.disconnect();
}
/**
* 处理请求参数
*
* @param request
* @return
* @throws IOException
*/
private String dealParam(HttpRequest request) throws IOException
{
StringBuilder builder = new StringBuilder();
Iterator<Entry<String, List<String>>> iterator = request.getParams();
int count = 0;
// 遍历请求参数
while (iterator.hasNext())
{
Entry<String, List<String>> entry = iterator.next();
List<String> list = entry.getValue();
for (String string : list)
{
if (count > 0)
{
builder.append("&");
}
builder.append(entry.getKey()).append("=");
if (request.getMethod() == RequestMethod.GET)
{
builder.append(URLEncoder.encode(string, request.getCharset()));
}
else
{
builder.append(string);
}
count++;
}
}
return builder.toString();
}
/**
* 出错时执行
*
* @param code
* @param stream
* @throws IOException
*/
public abstract void onError(int code, InputStream stream)
throws IOException;
/**
* 成功时执行
*
* @param code
* @param stream
* @throws IOException
*/
public abstract void onSuccess(int code, InputStream stream)
throws IOException;
}为了方便测试，简单的编写一个Servlet，代码如下：
package com.jhq.wx.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Test extends HttpServlet
{
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
System.out.println(request.getParameter("p1"));
System.out.println(request.getParameter("p2"));
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException
{
request.setCharacterEncoding("UTF-8");
System.out.println(request.getParameter("p1"));
System.out.println(request.getParameter("p2"));
}
}最后编写一个测试类，测试模拟表单提交
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
public class Test
{
public static void main(String[] args)
{
HttpRequest request = new HttpRequest("http://127.0.0.1/wx/s");
request.addParam("p1", "123");
request.addParam("p2", "蒋固金");
request.setMethod(RequestMethod.POST);
HttpClient client = new HttpClient()
{
@Override
public void onSuccess(int code, InputStream stream) throws IOException
{
// 内容是文本，直接以缓冲字符流读取
BufferedReader reader = new BufferedReader(new InputStreamReader(
stream, "UTF-8"));
String data = null;
while ((data = reader.readLine()) != null)
{
System.out.print(data);
}
reader.close();
}
@Override
public void onError(int code, InputStream stream)
{
System.out.println("请求出现异常");
}
};
try
{
client.execute(request);
}
catch (IOException e)
{
e.printStackTrace();
}
}
}运行之后，我们可以看到服务端后台输出：
123
蒋固金
这样就完成了Java模拟表单提交的操作。