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三种方法实现java调用Restful接口

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1,基本介绍
Restful接口的调用，前端一般使用ajax调用，后端可以使用的方法比较多，

本次介绍三种：

1.HttpURLConnection实现

2.HttpClient实现

3.Spring的RestTemplate

2，HttpURLConnection实现

@Controller
public class RestfulAction {
    @Autowired
    private UserService userService;
    // 修改
    @RequestMapping(value = "put/{param}", method = RequestMethod.PUT)
    public @ResponseBody String put(@PathVariable String param) {
        return "put:" + param;
    }
    // 新增
    @RequestMapping(value = "post/{param}", method = RequestMethod.POST)
    public @ResponseBody String post(@PathVariable String param,String id,String name) {
        System.out.println("id:"+id);
        System.out.println("name:"+name);
        return "post:" + param;
    }
    // 删除
    @RequestMapping(value = "delete/{param}", method = RequestMethod.DELETE)
    public @ResponseBody String delete(@PathVariable String param) {
        return "delete:" + param;
    }
    // 查找
    @RequestMapping(value = "get/{param}", method = RequestMethod.GET)
    public @ResponseBody String get(@PathVariable String param) {
        return "get:" + param;
    }
    // HttpURLConnection 方式调用Restful接口
    // 调用接口
    @RequestMapping(value = "dealCon/{param}")
    public @ResponseBody String dealCon(@PathVariable String param) {
        try {
            String url = "http://localhost:8080/tao-manager-web/";
            url+=(param+"/xxx");
            URL restServiceURL = new URL(url);
            HttpURLConnection httpConnection = (HttpURLConnection) restServiceURL
                    .openConnection();
            //param 输入小写，转换成 GET POST DELETE PUT 
            httpConnection.setRequestMethod(param.toUpperCase());
//            httpConnection.setRequestProperty("Accept", "application/json");
            if("post".equals(param)){
                //打开输出开关
                httpConnection.setDoOutput(true);
//                httpConnection.setDoInput(true);
                //传递参数
                String input = "&id="+ URLEncoder.encode("abc", "UTF-8");
                input+="&name="+ URLEncoder.encode("啊啊啊", "UTF-8");
                OutputStream outputStream = httpConnection.getOutputStream();
                outputStream.write(input.getBytes());
                outputStream.flush();
            }
            if (httpConnection.getResponseCode() != 200) {
                throw new RuntimeException(
                        "HTTP GET Request Failed with Error code : "
                                + httpConnection.getResponseCode());
            }
            BufferedReader responseBuffer = new BufferedReader(
                    new InputStreamReader((httpConnection.getInputStream())));
            String output;
            System.out.println("Output from Server:  \n");
            while ((output = responseBuffer.readLine()) != null) {
                System.out.println(output);
            }
            httpConnection.disconnect();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "success";
    }
}

3.HttpClient实现

复制代码
package com.taozhiye.controller;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.taozhiye.entity.User;
import com.taozhiye.service.UserService;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;

@Controller
public class RestfulAction {  
    @Autowired
    private UserService userService;
    // 修改
    @RequestMapping(value = "put/{param}", method = RequestMethod.PUT)
    public @ResponseBody String put(@PathVariable String param) {
        return "put:" + param;
    }
    // 新增
    @RequestMapping(value = "post/{param}", method = RequestMethod.POST)
    public @ResponseBody User post(@PathVariable String param,String id,String name) {
        User u = new User();
        System.out.println(id);
        System.out.println(name);
        u.setName(id);
        u.setPassword(name);
        u.setEmail(id);
        u.setUsername(name);
        return u;
    }    
    // 删除
    @RequestMapping(value = "delete/{param}", method = RequestMethod.DELETE)
    public @ResponseBody String delete(@PathVariable String param) {
        return "delete:" + param;
    }
    // 查找
    @RequestMapping(value = "get/{param}", method = RequestMethod.GET)
    public @ResponseBody User get(@PathVariable String param) {
        User u = new User();
        u.setName(param);
        u.setPassword(param);
        u.setEmail(param);
        u.setUsername("爱爱啊");
        return u;
    }
    @RequestMapping(value = "dealCon2/{param}")
    public @ResponseBody User dealCon2(@PathVariable String param) {
        User user = null;
        try {
            HttpClient client = HttpClients.createDefault();
            if("get".equals(param)){
                HttpGet request = new HttpGet("http://localhost:8080/tao-manager-web/get/"
                        +"啊啊啊");
                request.setHeader("Accept", "application/json");
                HttpResponse response = client.execute(request);
                HttpEntity entity = response.getEntity();
                ObjectMapper mapper = new ObjectMapper();
                user = mapper.readValue(entity.getContent(), User.class);
            }else if("post".equals(param)){
                HttpPost request2 = new HttpPost("http://localhost:8080/tao-manager-web/post/xxx");
                List<NameValuePair> nvps = new ArrayList<NameValuePair>();  
                nvps.add(new BasicNameValuePair("id", "啊啊啊"));  
                nvps.add(new BasicNameValuePair("name", "secret"));
                UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(nvps, "GBK");
                request2.setEntity(formEntity);
                HttpResponse response2 = client.execute(request2);
                HttpEntity entity = response2.getEntity();
                ObjectMapper mapper = new ObjectMapper();
                user = mapper.readValue(entity.getContent(), User.class);
            }else if("delete".equals(param)){
            }else if("put".equals(param)){
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return user;
    } 
}

4.Spring的RestTemplate

springmvc.xml增加

<!-- 配置RestTemplate -->
    <!--Http client Factory -->
    <bean id="httpClientFactory"
        class="org.springframework.http.client.SimpleClientHttpRequestFactory">
        <property name="connectTimeout" value="10000" />
        <property name="readTimeout" value="10000" />
    </bean>

    <!--RestTemplate -->
    <bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
        <constructor-arg ref="httpClientFactory" />
    </bean>

controller


@Controller
public class RestTemplateAction {
    @Autowired
    private RestTemplate template;
    @RequestMapping("RestTem")
    public @ResponseBody User RestTem(String method) {
        User user = null;
        //查找
        if ("get".equals(method)) {
            user = template.getForObject(
                    "http://localhost:8080/tao-manager-web/get/{id}",
                    User.class, "呜呜呜呜");
            //getForEntity与getForObject的区别是可以获取返回值和状态、头等信息
            ResponseEntity<User> re = template.
                    getForEntity("http://localhost:8080/tao-manager-web/get/{id}",
                    User.class, "呜呜呜呜");
            System.out.println(re.getStatusCode());
            System.out.println(re.getBody().getUsername());
        //新增
        } else if ("post".equals(method)) {
            HttpHeaders headers = new HttpHeaders();
            headers.add("X-Auth-Token", UUID.randomUUID().toString());
            MultiValueMap<String, String> postParameters = new LinkedMultiValueMap<String, String>();
            postParameters.add("id", "啊啊啊");
            postParameters.add("name", "部版本");
            HttpEntity<MultiValueMap<String, String>> requestEntity = new HttpEntity<MultiValueMap<String, String>>(
                    postParameters, headers);
            user = template.postForObject(
                    "http://localhost:8080/tao-manager-web/post/aaa", requestEntity,
                    User.class);
        //删除
        } else if ("delete".equals(method)) {
            template.delete("http://localhost:8080/tao-manager-web/delete/{id}","aaa");
        //修改
        } else if ("put".equals(method)) {
            template.put("http://localhost:8080/tao-manager-web/put/{id}",null,"bbb");
        }
        return user;
    }
}