在非anctivity类中使用Toast

本文主要是介绍在非anctivity类中使用Toast，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

最近在做android的项目，在子线程中访问网络资源，当网络访问出现异常时想用Toast提示用户。看了一下makeText方法的参数，
第一个就是Context，好的，写个局部变量，提供setter()、getter()方法，把主线程的Context传过来，执行，报错了：

04-09 21:14:44.412 7398-7544/com.explame.cuttese.circle3 E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-2376 Process: com.explame.cuttese.circle3, PID: 7398 java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() at android.os.Handler.<init>(Handler.java:200) at android.os.Handler.<init>(Handler.java:114) at android.widget.Toast$TN.<init>(Toast.java:345) at android.widget.Toast.<init>(Toast.java:100) at android.widget.Toast.makeText(Toast.java:257) at com.explame.cuttese.circle3.service.HttpClientService.run(HttpClientService.java:85)
告诉我缺少Looper.prepare() ，好的加上就是了，别忘了把Looper.loop()也加上，结果OK，Toast就能正常显示了。
终点代码：

Looper.prepare();Toast.makeText(context,"网络连接出现异常，请检查网络连接后重试。",Toast.LENGTH_LONG).show();Looper.loop();

全部代码如下：
RegisterActivity.class

package com.explame.cuttese.circle3;import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;import com.explame.cuttese.circle3.service.HttpClientService;
import com.explame.cuttese.circle3.service.MD5;import org.json.JSONObject;public class RegisterActivity extends Activity {private Button register;private EditText registerUserNameEdit;private EditText registerUserPasswordEdit;private EditText registerUserPhoneEdit;private ProgressDialog progressDialog;private String userName;private String userPassword;private String userPhoene;private Handler handler;private static final int REGISTER_SIGN = 0x0001;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_register);registerUserNameEdit = (EditText)findViewById(R.id.register_user_name);registerUserPasswordEdit = (EditText)findViewById(R.id.register_user_password);registerUserPhoneEdit = (EditText)findViewById(R.id.register_user_phone);register = (Button)findViewById(R.id.register_button);Intent myIntent = getIntent();userName = myIntent.getStringExtra("userName");userPassword = myIntent.getStringExtra("userPassword");if(null!=userName&&!"".equals(userName)){registerUserNameEdit.setText(userName.trim());}if(null!=userPassword&&!"".equals(userPassword)){registerUserPasswordEdit.setText(userPassword.trim());}myHandler();register.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v){userName = registerUserNameEdit.getText().toString().trim();userPassword = registerUserPasswordEdit.getText().toString().trim();userPhoene = registerUserPhoneEdit.getText().toString().trim();if("".equals(userName)){Toast.makeText(RegisterActivity.this,"请填写用户名。",Toast.LENGTH_SHORT).show();}else if("".equals(userPassword)){Toast.makeText(RegisterActivity.this,"请填写密码。",Toast.LENGTH_SHORT).show();}else if("".equals(userPhoene)){Toast.makeText(RegisterActivity.this,"请填写手机号。",Toast.LENGTH_SHORT).show();}else{progressDialog = ProgressDialog.show(RegisterActivity.this,"","加载中，请稍等……");//密码加密try{userPassword = new MD5().EncryptByMD5(userPassword);}catch (Exception e){Toast.makeText(RegisterActivity.this,"请重试。",Toast.LENGTH_SHORT).show();return;}//发起网络请求HttpClientService hcs = new HttpClientService();hcs.setProgressDialog(progressDialog);hcs.setContext(RegisterActivity.this);hcs.setHandler(handler);hcs.setSign(REGISTER_SIGN);hcs.setUrl(getResources().getString(R.string.url) + "userService/userRegister/" + userName + "," + userPassword + "," + userPhoene + ",100.100.100.100,80");hcs.start();hcs.interrupt();}}});}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.menu_register, menu);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.int id = item.getItemId();//noinspection SimplifiableIfStatementif (id == R.id.action_settings) {return true;}return super.onOptionsItemSelected(item);}public void myHandler() {handler = new Handler(){@Overridepublic void handleMessage(Message msg) {progressDialog.dismiss();   //关闭ProgressDialogif(msg.what==REGISTER_SIGN){try {String result = msg.obj.toString();JSONObject jo = new JSONObject(result);String state = jo.get("state").toString().trim();if("true".equals(state)){Toast.makeText(RegisterActivity.this,"登陆ID为："+jo.getString("loginId"),Toast.LENGTH_SHORT).show();}else{Toast.makeText(RegisterActivity.this,"网络异常，请检查网络设置后重试",Toast.LENGTH_SHORT).show();}}catch (Exception e){}}}};}
}

HttpClientService.class

package com.explame.cuttese.circle3.service;import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
import android.widget.Toast;import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;/*** Created by lenovo on 2015/4/30.*/
public class HttpClientService extends Thread{private String url = "";private Handler handler = null;private int sign = 0;private ProgressDialog progressDialog;private Context context;public String getUrl() {return url;}public void setUrl(String url) {this.url = url;}private Handler getHandler() {return handler;}public void setHandler(Handler handler) {this.handler = handler;}private int getSign() {return sign;}public void setSign(int sign) {this.sign = sign;}public void setProgressDialog(ProgressDialog progressDialog){this.progressDialog = progressDialog;}private ProgressDialog getProgressDialog() {return progressDialog;}public void setContext(Context context) {this.context = context;}private Context getContext() {return context;}@Overridepublic void run() {String result = "";HttpClient httpClient = new DefaultHttpClient();HttpGet request = new HttpGet(getUrl().replace(" ","%20"));HttpResponse response = null;try {response = httpClient.execute(request);if(response.getStatusLine().getStatusCode()== HttpStatus.SC_OK){result = EntityUtils.toString(response.getEntity());}}catch(Exception e){e.printStackTrace();progressDialog.dismiss();Looper.prepare();Toast.makeText(context,"网络连接出现异常，请检查网络连接后重试。",Toast.LENGTH_LONG).show();Looper.loop();}Message message = getHandler().obtainMessage();message.obj = result;message.what = sign;Log.v("msg.obj",result);getHandler().sendMessage(message);}
}