使用 Apache ResponseHandler 处理 Http 返回信息

org.apache.http.util.EntityUtils

toString

org.apache.http.client.ResponseHandler

EntityUtils

1 新建 CustomResponse 类作为所有 Http 接口的返回信息

public class CustomResponse {

public static final int OK = 100;
public static final int ERROR = 999;

public CustomResponse() {}

public CustomResponse(int code, String msg) {
this.code = code;
this.msg = msg;
}

private int code;

private String msg;

public int getCode() {
return code;
}

public void setCode(int code) {
this.code = code;
}

public String getMsg() {
return msg;
}

public void setMsg(String msg) {
this.msg = msg;
}

}

2 修改 LoginService 的返回信息，由一个普通的字符串变为 CustomResponse 类实例的 JSON 字符串

import java.io.IOException;
import java.io.OutputStream;

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

import com.google.gson.Gson;

import util.CustomResponse;

public class LoginService extends HttpServlet {

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
OutputStream outputStream = response.getOutputStream();
response.setHeader("content-type", "application/json;charset=UTF-8");
CustomResponse result = null;
if (username == null) {
result = new CustomResponse(CustomResponse.ERROR, "Post:请输入用户名！");
} else if (password == null) {
result = new CustomResponse(CustomResponse.ERROR, "Post:请输入密码！");
} else if (!username.equals("unique")) {
result = new CustomResponse(CustomResponse.ERROR, "Post:用户名错误！");
} else if (!password.equals("ASDF")) {
result = new CustomResponse(CustomResponse.ERROR, "Post:密码错误！");
} else {
result = new CustomResponse(CustomResponse.ERROR, "Post:验证通过~~");
}
outputStream.write(new Gson().toJson(result).getBytes("UTF-8"));
}

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
OutputStream outputStream = response.getOutputStream();
response.setHeader("content-type", "application/json;charset=UTF-8");
CustomResponse result = null;
if (username == null) {
result = new CustomResponse(CustomResponse.ERROR, "Get:请输入用户名！");
} else if (password == null) {
result = new CustomResponse(CustomResponse.ERROR, "Get:请输入密码！");
} else if (!username.equals("unique")) {
result = new CustomResponse(CustomResponse.ERROR, "Get:用户名错误！");
} else if (!password.equals("ASDF")) {
result = new CustomResponse(CustomResponse.ERROR, "Get:密码错误！");
} else {
result = new CustomResponse(CustomResponse.ERROR, "Get:验证通过~~");
}
outputStream.write(new Gson().toJson(result).getBytes("UTF-8"));
}

}

3 修改

public static final String invokeHttpGet(String uri)

方法逻辑

public static final String invokeHttpGet(String uri)
throws ClientProtocolException, IOException {
CloseableHttpClient client = HttpClients.createDefault();
CloseableHttpResponse response = null;
HttpGet httpGet = new HttpGet(uri);
try {
response = client.execute(httpGet);
HttpEntity entity = response.getEntity();
return EntityUtils.toString(entity);
} finally {
release(client, response);
}
}

public static final CustomResponse invokeHttpGetS(String uri)
throws ClientProtocolException, IOException {
CloseableHttpClient client = HttpClients.createDefault();
HttpGet httpGet = new HttpGet(uri);
ResponseHandler<CustomResponse> responseHandler = new ResponseHandler<CustomResponse>() {
@Override
public CustomResponse handleResponse(HttpResponse response)
throws ClientProtocolException, IOException {
StatusLine statusLine = response.getStatusLine();
if (statusLine.getStatusCode() >= 300) {
throw new HttpResponseException(
statusLine.getStatusCode(),
statusLine.getReasonPhrase());
}
HttpEntity entity = response.getEntity();
if (entity == null) {
throw new ClientProtocolException("Response contains no content!");
}
ContentType contentType = ContentType.getOrDefault(entity);
Charset charset = contentType.getCharset();
Reader reader = new InputStreamReader(entity.getContent(), charset);
Gson gson = new GsonBuilder().serializeNulls().create();
return gson.fromJson(reader, CustomResponse.class);
}
};
return client.execute(httpGet, responseHandler);
}

ResponseHandler

handleResponse

HttpClient

4 单元测试

@Test
public void test() throws ClientProtocolException, IOException {
String uri1 = "http://localhost:8080/Service/login";
String uri2 = "http://localhost:8080/Service/login?username=unique";
String uri3 = "http://localhost:8080/Service/login?password=ASDF";
String uri4 = "http://localhost:8080/Service/login?username=unique1&password=ASDF";
String uri5 = "http://localhost:8080/Service/login?username=unique&password=ASDF2";
String uri6 = "http://localhost:8080/Service/login?username=unique&password=ASDF";

assertEquals("Get:请输入用户名！",
HttpClientTool.invokeHttpGetS(uri1).getMsg());
assertEquals("Get:请输入密码！",
HttpClientTool.invokeHttpGetS(uri2).getMsg());
assertEquals("Get:请输入用户名！",
HttpClientTool.invokeHttpGetS(uri3).getMsg());
assertEquals("Get:用户名错误！",
HttpClientTool.invokeHttpGetS(uri4).getMsg());
assertEquals("Get:密码错误！",
HttpClientTool.invokeHttpGetS(uri5).getMsg());
assertEquals("Get:验证通过~~",
HttpClientTool.invokeHttpGetS(uri6).getMsg());
}