android网络请求

从活动内发送网络请求，代码如下：

package com.example.shuilangyizu;

import android.app.ActionBar;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.device.ScanManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Vibrator;
import android.provider.Settings;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.animation.Animation;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;import com.example.shuilangyizu.util.UrlRequestUtil;

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

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


/**
 * 主活动
 */
public class MainActivity extends AppCompatActivity {
    private final static String SCAN_ACTION = ScanManager.ACTION_DECODE;//default action
    private ActionBar actionBar;
    private Vibrator mVibrator;
    private Animation buttonPress;
    String projectPath = "";
    //获取所有数据请求路径
    private String systemUrl = "";//创建Handler对象mHandler,mHandler是Handler类型的成员变量
    public Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            Object obj = msg.obj;
            int what = msg.what;
            if (what==1){
                
            }
            if (what==2){
                
            }
        }
    };

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Window window = getWindow();
        window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        setContentView(R.layout.activity_main);

        mVibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
        actionBar = getActionBar();
        if (actionBar!=null){
            actionBar.show();
        }

        Thread thread = new Thread(){
            @Override
            public void run(){
                //调用发送请求方法
                Map<String,Object> paramMap = new HashMap<>();
                paramMap.put("what","1");
                projectPath = getString(R.string.projectPath);
                stockupSystemUrl = getString(R.string.systemUrl);
                UrlRequestUtil.sendPostRequest(mHandler, projectPath+systemUrl,paramMap);
            }
        };
        thread.start();
    }

}

网络请求工具类代码如下：

 特别注意这两行代码：

//dStream.writeBytes(paramString);//中文会乱码
//dStream.write(paramString.getBytes());//中文不会乱码

package com.example.shuilangyizu.util;

import android.os.Handler;
import android.os.Message;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Map;

/**
 * 网络请求工具类
 */
public class UrlRequestUtil {

    /**
     * 发送post请求
     *
     * @param mHandler :
     * @param url:请求发送地址
     * @param paramMap:请求发送的参数
     *                无论哪里调用必须存入一个消息标记what数字类型，用于区分消息提醒的位置。
     *                what取值范围如下定义（有新的消息提醒位置后续定义）：
     */
    public static void sendPostRequest(Handler mHandler,String url, Map<String,Object> paramMap){
        BufferedReader br = null;
        HttpURLConnection conn= null;
        try{
            int what = paramMap.get("what")==null?0:Integer.parseInt(paramMap.get("what").toString());
            URL reqURL = new URL(url);
            conn=(HttpURLConnection) reqURL.openConnection();
            conn.setRequestMethod("POST");
            conn.setDoOutput(true);
            String paramFormat ="";
            for (String key : paramMap.keySet()) {
                String value = paramMap.get(key) == null ? "" : paramMap.get(key).toString();
                if (paramFormat!=""){
                    paramFormat = paramFormat + "&" + key + "=" + value;
                }else{
                    paramFormat = key + "=" + value;
                }
            }
            String paramString= String.format(paramFormat);
            //设置参数
            DataOutputStream dStream = new DataOutputStream(conn.getOutputStream());
            //dStream.writeBytes(paramString);//中文会乱码
            dStream.write(paramString.getBytes());//中文不会乱码
            dStream.close();
            //打开网络通信输入流
            InputStream is = conn.getInputStream();
            //通过is创建InputStreamReader对象
            InputStreamReader isr = new InputStreamReader(is, "UTF-8");
            //通过isr创建BufferedReader对象
            br = new BufferedReader(isr);
            StringBuilder sb = new StringBuilder();
            String line;
            while((line = br.readLine())!= null){
                sb.append(line);
            }
            //创建消息
            Message msg = new Message();
            //消息标记
            msg.what = what;
            //设置消息内容
            msg.obj = sb.toString();
            //发送消息到主线程
            mHandler.sendMessage(msg);
        }catch(Exception e){
            e.printStackTrace();
        }finally {
            if (conn != null) {
                conn.disconnect();
            }
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}