最近帮一个朋友做一个项目需要调用翻译

技术选型的时候考虑到了使用百度翻译和有道翻译，因为我们只是演示使用，只考虑免费套餐

百度翻译是每个月可以免费调用200万个关键字，有道翻译每小时可以调用1千个关键字，综合考虑选百度翻译。

一、注册百度翻译平台账号

官网地址：https://fanyi-api.baidu.com/product/11

文档地址：https://api.fanyi.baidu.com/doc/21

注册完成，免费试用高级账号，创建应用

下面有app_id和秘钥

二、demo

1、Md5.java

import java.io.*;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * MD5编码相关的类
 *
 * 
 */
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 | UnsupportedEncodingException e) {
            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);

    }

}

2、TeansApi.java

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;
    }

}

3、HttpGet.java

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 {
        }
    };

}

4、Main.java

package translate;


import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

public class Main {

    // 在平台申请的APP_ID 详见 http://api.fanyi.baidu.com/api/trans/product/desktop?req=developer
    private static final String APP_ID = "xxxx";
    private static final String SECURITY_KEY = "xxxx";

    public static void main(String[] args) {
        TransApi api = new TransApi(APP_ID, SECURITY_KEY);

        String query = "聚乙烯";
        String transResultStr = api.getTransResult(query, "zh", "en");
        JSONObject result = JSONObject.parseObject(transResultStr);
        JSONArray jsonArray = result.getJSONArray("trans_result");
        JSONObject jsonObject = jsonArray.getJSONObject(0);
        String dst = jsonObject.getString("dst");
        System.out.println(dst);
    }

}

注意修改APP_ID和秘钥