中英翻译（基于百度翻译）

先来看效果图

只做了简单的在线翻译，语音翻译和图片翻译都要钱，哈哈

市面上有名气的翻译公司就是有道和百度了，有道尝试了一下，分为API和SDK两种，但是demo下载下来跑不了

百度的就是API，也很简单，就是通过百度的协议去请求他们的服务器，得到翻译后的值，每个月有200万的免费，够用了

百度文档地址http://api.fanyi.baidu.com/api/trans/product/apidoc#joinFile

步骤：

java版demo下载地址https://fanyiapp.cdn.bcebos.com/api/demo/java.zip

下面是核心代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/inputChinese"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入要翻译的中文"
        android:singleLine="true" />

    <EditText
        android:id="@+id/inputEnglish"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入要翻译的英文"
        android:singleLine="true" />

    <TextView
        android:id="@+id/translate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right"
        android:layout_margin="10dp"
        android:padding="10dp"
        android:text="翻译"
        android:textSize="20sp" />

    <TextView
        android:id="@+id/outputEnglish"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"
        tools:text="得到的英文" />

    <TextView
        android:id="@+id/outputChinese"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"
        tools:text="得到的中文" />

</LinearLayout>

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.EditText;
import android.widget.TextView;

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

public class MainActivity extends AppCompatActivity {
    private static final String APP_ID = "20190603000304432";
    private static final String SECURITY_KEY = "gZTcFc0TyR6tZS5FfmyA";
    private EditText inputChinese;
    private EditText inputEnglish;
    private TextView outputEnglish;
    private TextView outputChinese;
    private TextView translate;
    private TransApi api;
    private static final int CHINESE = 1;
    private static final int ENGLISH = 2;
    private static final String TO_ENGLISH = "en";
    private static final String TO_CHINESE = "zh";

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            String str = String.valueOf(msg.obj);
            String value = parserJson(str);
            switch (msg.what) {
                case CHINESE:
                    outputChinese.setText(value);
                    break;
                case ENGLISH:
                    outputEnglish.setText(value);
                    break;
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        api = new TransApi(APP_ID, SECURITY_KEY);
        translate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                translate(inputChinese.getText().toString(), TO_ENGLISH);
                translate(inputEnglish.getText().toString(), TO_CHINESE);
            }
        });
    }

    private void initView() {
        inputChinese = findViewById(R.id.inputChinese);
        inputEnglish = findViewById(R.id.inputEnglish);
        outputEnglish = findViewById(R.id.outputEnglish);
        outputChinese = findViewById(R.id.outputChinese);
        translate = findViewById(R.id.translate);
    }

    private void translate(final String chinese, final String toLanguage) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                String transResult = api.getTransResult(chinese, "auto", toLanguage);
                Message message = new Message();
                switch (toLanguage) {
                    case TO_CHINESE:
                        message.what = CHINESE;
                        break;
                    case TO_ENGLISH:
                        message.what = ENGLISH;
                        break;
                }
                message.obj = transResult;
                handler.sendMessage(message);
            }
        }).start();
    }

    private String parserJson(String str) {
        try {
            JSONObject jsonObject = new JSONObject(str);
            JSONArray trans_result = jsonObject.getJSONArray("trans_result");
            JSONObject result = trans_result.getJSONObject(0);
            String dst = result.getString("dst");
            return dst;
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return "";
    }
}

import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Map;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;

class HttpGet {
    protected static final int SOCKET_TIMEOUT = 10000; // 10S
    protected static final String GET = "GET";

    public static String get(String host, Map<String, String> params) {
        try {
            // 设置SSLContext
            SSLContext sslcontext = SSLContext.getInstance("TLS");
            sslcontext.init(null, new TrustManager[] { myX509TrustManager }, null);

            String sendUrl = getUrlWithQueryString(host, params);

            // System.out.println("URL:" + sendUrl);

            URL uri = new URL(sendUrl); // 创建URL对象
            HttpURLConnection conn = (HttpURLConnection) uri.openConnection();
            if (conn instanceof HttpsURLConnection) {
                ((HttpsURLConnection) conn).setSSLSocketFactory(sslcontext.getSocketFactory());
            }

            conn.setConnectTimeout(SOCKET_TIMEOUT); // 设置相应超时
            conn.setRequestMethod(GET);
            int statusCode = conn.getResponseCode();
            if (statusCode != HttpURLConnection.HTTP_OK) {
                System.out.println("Http错误码：" + statusCode);
            }

            // 读取服务器的数据
            InputStream is = conn.getInputStream();
            BufferedReader br = new BufferedReader(new InputStreamReader(is));
            StringBuilder builder = new StringBuilder();
            String line = null;
            while ((line = br.readLine()) != null) {
                builder.append(line);
            }

            String text = builder.toString();

            close(br); // 关闭数据流
            close(is); // 关闭数据流
            conn.disconnect(); // 断开连接

            return text;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (KeyManagementException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }

        return null;
    }

    public static String getUrlWithQueryString(String url, Map<String, String> params) {
        if (params == null) {
            return url;
        }

        StringBuilder builder = new StringBuilder(url);
        if (url.contains("?")) {
            builder.append("&");
        } else {
            builder.append("?");
        }

        int i = 0;
        for (String key : params.keySet()) {
            String value = params.get(key);
            if (value == null) { // 过滤空的key
                continue;
            }

            if (i != 0) {
                builder.append('&');
            }

            builder.append(key);
            builder.append('=');
            builder.append(encode(value));

            i++;
        }

        return builder.toString();
    }

    protected static void close(Closeable closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 对输入的字符串进行URL编码, 即转换为%20这种形式
     * 
     * @param input 原文
     * @return URL编码. 如果编码失败, 则返回原文
     */
    public static String encode(String input) {
        if (input == null) {
            return "";
        }

        try {
            return URLEncoder.encode(input, "utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

        return input;
    }

    private static TrustManager myX509TrustManager = new X509TrustManager() {

        @Override
        public X509Certificate[] getAcceptedIssuers() {
            return null;
        }

        @Override
        public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        }

        @Override
        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        }
    };

}

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * MD5编码相关的类
 *
 * @author wangjingtao
 */
public class MD5 {
    // 首先初始化一个字符数组，用来存放每个16进制字符
    private static final char[] hexDigits = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
            'e', 'f'};

    /**
     * 获得一个字符串的MD5值
     *
     * @param input 输入的字符串
     * @return 输入字符串的MD5值
     */
    public static String md5(String input) {
        if (input == null)
            return null;

        try {
            // 拿到一个MD5转换器（如果想要SHA1参数换成”SHA1”）
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            // 输入的字符串转换成字节数组
            byte[] inputByteArray = input.getBytes("utf-8");
            // inputByteArray是输入字符串转换得到的字节数组
            messageDigest.update(inputByteArray);
            // 转换并返回结果，也是字节数组，包含16个元素
            byte[] resultByteArray = messageDigest.digest();
            // 字符数组转换成字符串返回
            return byteArrayToHex(resultByteArray);
        } catch (NoSuchAlgorithmException e) {
            return null;
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 获取文件的MD5值
     *
     * @param file
     * @return
     */
    public static String md5(File file) {
        try {
            if (!file.isFile()) {
                System.err.println("文件" + file.getAbsolutePath() + "不存在或者不是文件");
                return null;
            }

            FileInputStream in = new FileInputStream(file);

            String result = md5(in);

            in.close();

            return result;

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    public static String md5(InputStream in) {

        try {
            MessageDigest messagedigest = MessageDigest.getInstance("MD5");

            byte[] buffer = new byte[1024];
            int read = 0;
            while ((read = in.read(buffer)) != -1) {
                messagedigest.update(buffer, 0, read);
            }

            in.close();

            String result = byteArrayToHex(messagedigest.digest());

            return result;
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    private static String byteArrayToHex(byte[] byteArray) {
        // new一个字符数组，这个就是用来组成结果字符串的（解释一下：一个byte是八位二进制，也就是2位十六进制字符（2的8次方等于16的2次方））
        char[] resultCharArray = new char[byteArray.length * 2];
        // 遍历字节数组，通过位运算（位运算效率高），转换成字符放到字符数组中去
        int index = 0;
        for (byte b : byteArray) {
            resultCharArray[index++] = hexDigits[b >>> 4 & 0xf];
            resultCharArray[index++] = hexDigits[b & 0xf];
        }

        // 字符数组组合成字符串返回
        return new String(resultCharArray);

    }

}

import java.util.HashMap;
import java.util.Map;

public class TransApi {
    private static final String TRANS_API_HOST = "http://api.fanyi.baidu.com/api/trans/vip/translate";

    private String appid;
    private String securityKey;

    public TransApi(String appid, String securityKey) {
        this.appid = appid;
        this.securityKey = securityKey;
    }

    public String getTransResult(String query, String from, String to) {
        Map<String, String> params = buildParams(query, from, to);
        return HttpGet.get(TRANS_API_HOST, params);
    }

    private Map<String, String> buildParams(String query, String from, String to) {
        Map<String, String> params = new HashMap<String, String>();
        params.put("q", query);
        params.put("from", from);
        params.put("to", to);

        params.put("appid", appid);

        // 随机数
        String salt = String.valueOf(System.currentTimeMillis());
        params.put("salt", salt);

        // 签名
        String src = appid + query + salt + securityKey; // 加密前的原文
        params.put("sign", MD5.md5(src));

        return params;
    }

}

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