【达内课程】网络通信之HTTP协议（2）

如何使用Android代码发送HTTP POST请求
1、创建URL对象

URL url = new URL("http://xxx");

2、创建HttpURLConnection对象

conn = url.openConnection()

3、设置消息方式和消息头

conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");

(multipart/form-date)

4、设置开启输出流
使用输出流输出请求参数

conn.setDoOutput(true);
os = conn.getOutputStream();
os.write("date=2016&number=00001".getBytes());
os.flush();

5、调用conn.getInputStream()发送请求并获取响应

is = conn.getInputStream()

6、解析响应数据，获取响应文本
is转换为String

在上一节的栗子上修改为POST

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;


public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button btn_connect;
    private EditText et_date;

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

        setViews();
    }


    private void setViews() {
        et_date = findViewById(R.id.et_date);
        btn_connect = findViewById(R.id.btn_connect);
        btn_connect.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn_connect:
                new Thread(){
                    @Override
                    public void run() {
                        try {
                            findFlightsByPost();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }.start();
                break;
        }
    }

    //使用Get方式发送请求 获取航班数据
    private void findFlightsByPost() throws IOException {
        //1、URL
        URL url = new URL("http://192.168.3.25:8888/android_jsp/flight_index.jsp");
        //2、HttpURLConnection
        HttpURLConnection conn =  (HttpURLConnection)url.openConnection();
        //3、setRequestMethod() setRequestProperty()
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
        //4、doOutput(true)
        conn.setDoOutput(true);
        String d = et_date.getText().toString();
        String param = "date="+d;
        OutputStream os = conn.getOutputStream();
        os.write(param.getBytes("utf-8"));
        os.flush();
        //5、conn.InputStream
        InputStream is = conn.getInputStream();
        //6、is转成String
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();
        String line = "";
        while ((line=reader.readLine())!=null){
            sb.append(line);
        }
        Log.d("info",sb.toString());
    }
}

Json

栗子：登录
首先，查看接口文档

增加权限

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

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

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

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;


public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button btn_add;
    private EditText et_number;
    private EditText et_password;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what){
                case ADD_CARD_SUCCESS:
                    Toast.makeText(MainActivity.this,"登录成功",Toast.LENGTH_SHORT).show();
                    break;
                case ADD_CARD_FAIL:
                    Toast.makeText(MainActivity.this,"登录失败："+msg.obj,Toast.LENGTH_SHORT).show();
                    break;
            }
        }
    };

    public static final int ADD_CARD_SUCCESS = 1;
    public static final int ADD_CARD_FAIL = 2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        setViews();
    }


    private void setViews() {
        et_number = findViewById(R.id.et_number);
        et_password = findViewById(R.id.et_password);
        btn_add = findViewById(R.id.btn_add);
        btn_add.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn_add:
                new Thread(){
                    @Override
                    public void run() {
                        try {
                            addCard();
                        } catch (IOException e) {
                            e.printStackTrace();
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                }.start();
                break;
        }
    }

    private void addCard() throws IOException, JSONException {
        //1、URL
        URL url = new URL("http://域名/site/login");
        //2、HttpURLConnection
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        //3、setRequestMethod  setRequestProperty()
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
        //4、doOutPut
        conn.setDoInput(true);
        OutputStream os = conn.getOutputStream();
        //5、构建参数
        String user_name = et_number.getText().toString();
        String password = et_password.getText().toString();
        String param = "user_name="+user_name+"&password="+password;
        os.write(param.getBytes("utf-8"));
        os.flush();
        //6、inputStream
        InputStream is = conn.getInputStream();
        //7、is转换成String
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();
        String line = "";
        while ((line = reader.readLine())!=null){
            sb.append(line);
        }

        String json = sb.toString();
        //7、解析json
        JSONObject obj = new JSONObject(json);
        String res = obj.getString("code");
        //8、发消息给Handler
        if(res.equals("0")){
            //成功
            handler.sendEmptyMessage(ADD_CARD_SUCCESS);
        }else{
            //失败
            Message msg = new Message();
            msg.what = ADD_CARD_FAIL;
            msg.obj = obj.getString("message");
            handler.sendMessage(msg);
        }
    }
}