ConnectivityManager类 判断网络是否可用进行设置

package androidthree_1509d.base;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.provider.Settings;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;
import com.google.gson.Gson;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.List;
import javax.net.ssl.HttpsURLConnection;

public class MainActivity extends AppCompatActivity {

private ListView listView;

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

listView = (ListView) findViewById(R.id.listview);

//获取网路信息
getDataFromNet();
}

public void getDataFromNet() {
//当进入页面时先判断网络状态是否连接可用...不可用,设置
if (isNetConnectioned()){
//获取网络数据
getData();
}else {
//当未连接时弹出对话框提醒
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("警告！");
builder.setMessage("网络未连接，是否去设置？");
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
//设置网络  Settings.ACTION_WIFI_SETTINGS
Intent intent = new Intent(Settings.ACTION_WIFI_SETTINGS);
startActivity(intent);
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
}
});
builder.show();
}
}

/**
* 判断网络是否可用的方法
* 异常：SecurityException: ConnectivityService:
*       Neither user 10033 nor current process has android.permission.ACCESS_NETWORK_STATE.
*       如果需要获取网络的状态,需要添加权限android.permission.ACCESS_NETWORK_STATE
*/
public boolean isNetConnectioned() {
//1. 获取网络连接对象
ConnectivityManager service = (ConnectivityManager) MainActivity.this.getSystemService(Context.CONNECTIVITY_SERVICE);

//2. 获取网络连接的信息
NetworkInfo info = service.getActiveNetworkInfo();

//3. 信息不为空时，就代表网络可用
if (info != null){
return  info.isAvailable();
}
return false;
}

//获取网络数据
public void getData() {
AsyncTask<String,String,String> task = new AsyncTask<String, String, String>() {
@Override
protected String doInBackground(String... strings) {
try {
//连接路径
String path = "https://suggest.taobao.com/sug?code=utf-8&q=%E6%98%BE%E7%A4%BA%E5%99%A8";
//连接网络
URL url = new URL(path);
HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(5000);
connection.setReadTimeout(5000);
//响应数据
int responseCode = connection.getResponseCode();
if (responseCode==200){
InputStream inputStream = connection.getInputStream();
String json = streamToString(inputStream,"utf-8");
return json;
}
} catch (Exception e) {
e.printStackTrace();
}

return null;
}

@Override
protected void onPostExecute(String json) {
ResultBean resultBean = new Gson().fromJson(json, ResultBean.class);
List<List<String>> list = resultBean.getResult();
//设置适配器
MyAdapter adapter = new MyAdapter(MainActivity.this, list);
listView.setAdapter(adapter);
}
};
task.execute();
}

private String streamToString(InputStream inputStream, String gbk) {
try {
//转换流
InputStreamReader streamReader = new InputStreamReader(inputStream, gbk);
//缓冲流
BufferedReader reader = new BufferedReader(streamReader);
//缓冲区
StringBuilder builder = new StringBuilder();

//读取数据
String s = null;
while ((s=reader.readLine())!=null){
builder.append(s);
}

return  builder.toString();
} catch (Exception e) {
e.printStackTrace();
}
return  null;
}
}

package androidthree_1509d.base;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import java.util.List;

public class MyAdapter extends BaseAdapter{
private Context context;
private List<List<String>> list;

public MyAdapter(Context context, List<List<String>> list) {
this.context = context;
this.list = list;
}

@Override
public int getCount() {
return list.size();
}

@Override
public Object getItem(int i) {
return list.get(i);
}

@Override
public long getItemId(int i) {
return i;
}

@Override
public View getView(int i, View view, ViewGroup viewGroup) {
ViewHolder holder = null;
if (view == null){
view = View.inflate(context, R.layout.item_layout, null);

holder = new ViewHolder();

//查找控件
holder.name = view.findViewById(R.id.name);

view.setTag(holder);
}else{
holder = (ViewHolder) view.getTag();
}

//获取数据重新赋值
holder.name.setText(list.get(i).get(0)+"      "+list.get(i).get(1));
return view;
}

static class ViewHolder{
TextView name;
}
}

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

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