Android开发之使用AsyncTask实现实时翻译

最近在做自己的安卓软件，于是乎就自己做了个翻译功能，主要方式是使用AsyncTask实现异步处理，翻译调用的互联网接口是有道提供的API。

方法很简单，通过HttpGET和HttpResponse获得String，再将json数据解析即可。

在AsynTask实现类中，输入是String，在doInBackground方法里主要实现目标String的获取。而在onPostExecute方法里主要实现获取后对结果result的处理与解析。

其他过程就没啥好说的了：具体代码如下:

package com.example.myallfunprojects;

import java.io.IOException;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.Manifest.permission;
import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class YouDaoTranslation extends Activity{
//控件
private Button btn_translate;
private EditText edit;
private TextView tv_result;
//判断是否有网络
private ConnectivityManager connManager;
private boolean hasNetwork = false;
//进行有道翻译时用到的常量
private String YouDaoBaseUrl = "http://fanyi.youdao.com/openapi.do";
private String YouDaoDocType = "json";
private String YouDaoVersion = "1.1";
private String YouDaoType = "data";
private String YouDaoKeyFrom = "MyAllFunction2";
private String APIKey = "297337179";
private String search_Content;

//数据保存使用
private String source_text = null;
private String resultmessage = null;
private SharedPreferences preference;
private Editor editor;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.youdao_layout);
init();

preference = getPreferences(Context.MODE_PRIVATE);
editor = preference.edit();

edit.setText(preference.getString("source_text", ""));
tv_result.setText(preference.getString("message", ""));
//判断网络状态
connManager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
btn_translate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
NetworkInfo netinfo = connManager.getActiveNetworkInfo();
// TODO Auto-generated method stub
//先检查网络状态
if (netinfo == null)
{
hasNetwork = false;
Toast.makeText(getApplicationContext(), "当前不存在网络,请检查设置",
Toast.LENGTH_SHORT).show();
}
else
{
hasNetwork = true;
search_Content = edit.getText().toString().trim();
source_text = search_Content;
new Translate_Asynctask().execute(search_Content);
}
}
});
}

public void init()
{
btn_translate = (Button) findViewById(R.id.btn_translate);
edit = (EditText) findViewById(R.id.et_text);
tv_result = (TextView) findViewById(R.id.result_text);
}
/**
* 通过Async实现异步操作
* @author sjm
*
*/
private class Translate_Asynctask extends AsyncTask<String, Void, String>
{
//在执行时查询
@Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
if (hasNetwork == false) {
return null;
}
String Url = YouDaoBaseUrl+"?keyfrom="+YouDaoKeyFrom+"&key="+APIKey+
"&type="+YouDaoType+"&doctype="+YouDaoDocType+"&version="+YouDaoVersion+
"&q="+params[0];
String result = null;
//HttpGet
HttpGet httpGet = new HttpGet(Url);
//使用execute方法发送HTTPGET请求，并获得HTTPResponse响应
try {
HttpResponse httpResponse = new DefaultHttpClient().execute(httpGet);
if (httpResponse.getStatusLine().getStatusCode() == 200) {
result = EntityUtils.toString(httpResponse.getEntity());
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return result;
}

@Override
protected void onCancelled() {
// TODO Auto-generated method stub
super.onCancelled();
}

@Override
protected void onCancelled(String result) {
// TODO Auto-generated method stub
super.onCancelled(result);
}

@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
if (result != null) {
try {
JSONArray jsonarray = new JSONArray("["+result+"]");
String message = null;
for (int i = 0; i < jsonarray.length(); i++) {
JSONObject object = jsonarray.getJSONObject(i);
if (object != null) {
String errorCode = object.getString("errorCode");
if (errorCode.equals("20")) {
Toast.makeText(getApplicationContext(), "要翻译的文本过长", Toast.LENGTH_SHORT);
}
else if (errorCode.equals("30")) {
Toast.makeText(getApplicationContext(), "无法进行有效的翻译", Toast.LENGTH_SHORT);
}
else if (errorCode.equals("40")) {
Toast.makeText(getApplicationContext(), "不支持的语言类型", Toast.LENGTH_SHORT);
}
else if (errorCode.equals("50")) {
Toast.makeText(getApplicationContext(), "无效的key", Toast.LENGTH_SHORT);
}
else
{
//取得要翻译的内容
String query = object.getString("query");
message = query;
String translation = object.getString("translation");
message += "\t"+translation;
if (object.has("basic")) {
JSONObject basic_object = object.getJSONObject("basic");
if (basic_object.has("phonetic")) {
String phonetic = basic_object.getString("phonetic");
message += "\n\t"+ phonetic;
}
if (basic_object.has("explains")) {
String explains = basic_object.getString("explains");
message += "\n\t" + explains;
}
}
if (object.has("web")) {
String web = object.getString("web");
JSONArray webarray = new JSONArray("["+web+"]");
message += "\n网络释义:";
JSONArray webArray = webarray.getJSONArray(0);
int count = 0;
while(!webArray.isNull(count)){

if (webArray.getJSONObject(count).has("key"))
{
String key = webArray.getJSONObject(count).getString("key");
message += "\n\t<"+(count+1)+">" + key;
}
if (webArray.getJSONObject(count).has("value"))
{
String value = webArray.getJSONObject(count).getString("value");
message += "\n\t   " + value;
}
count++;
}
}
}
}
}
resultmessage = message;
tv_result.setText(message);
editor.putString("source_text", source_text);
editor.putString("message", resultmessage);
editor.commit();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
else
tv_result.setText("无网络，无法执行");
}

@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
}

@Override
protected void onProgressUpdate(Void... values) {
// TODO Auto-generated method stub
super.onProgressUpdate(values);
}

}
}