使用之前需要獲取對應的專案API_KEY，SECRET_KEY，這些引數在使用API的時候必須用到，用於生成access_token。
如何獲取這些引數：在百度開發者中心申請一個“通用文字識別”專案，然後就可以獲取到這些引數。

1、pom檔案

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.within</groupId>
    <artifactId>baiduSearch</artifactId>
    <version>1.0-SNAPSHOT</version>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <dependencies>
    <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.2.46</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.5</version>
    </dependency>
    <dependency>
        <groupId>com.vaadin.external.google</groupId>
        <artifactId>android-json</artifactId>
        <version>0.0.20131108.vaadin1</version>
    </dependency>
</dependencies>

</project>
 

 2、獲取access_token

package search;

/**
 * Created by within on 2018/10/9.
 */
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.List;
import java.util.Map;
/**
 * 獲取token類
 *
 * @Author : within
 */

public class AuthService {

    /**
     * 獲取許可權token
     * @return 返回示例：
     * {
     * "access_token": "24.460da4889caad24cccdb1fea17221975.2592000.1491995545.282335-1234567",
     * "expires_in": 2592000
     * }
     */
    public static String getAuth() {
        // 官網獲取的 API Key 更新為你註冊的
        String clientId = "0ddYMfgtVSqcE9qMQxHhZ4Yc";
        // 官網獲取的 Secret Key 更新為你註冊的
        String clientSecret = "XXXNKZlv1gi60a04pzABadI9KgDbfkRM";
        return getAuth(clientId, clientSecret);
    }

    /**
     * 獲取API訪問token
     * 該token有一定的有效期，需要自行管理，當失效時需重新獲取.
     * @param ak - 百度雲官網獲取的 API Key
     * @param sk - 百度雲官網獲取的 Securet Key
     * @return assess_token 示例：
     * "24.460da4889caad24cccdb1fea17221975.2592000.1491995545.282335-1234567"
     */
    private static String getAuth(String ak, String sk) {
        // 獲取token地址
        String authHost = "https://aip.baidubce.com/oauth/2.0/token?";
        String getAccessTokenUrl = authHost
                // 1\. grant_type為固定引數
                + "grant_type=client_credentials"
                // 2\. 官網獲取的 API Key
                + "&client_id=" + ak
                // 3\. 官網獲取的 Secret Key
                + "&client_secret=" + sk;
        try {
            URL realUrl = new URL(getAccessTokenUrl);
            // 開啟和URL之間的連線
            HttpURLConnection connection = (HttpURLConnection) realUrl.openConnection();
            connection.setRequestMethod("GET");
            connection.connect();
            // 獲取所有響應頭欄位
            Map<String, List<String>> map = connection.getHeaderFields();
            // 遍歷所有的響應頭欄位
            for (String key : map.keySet()) {
                System.err.println(key + "--->" + map.get(key));
            }
            // 定義 BufferedReader輸入流來讀取URL的響應
            BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            StringBuilder result = new StringBuilder();
            String line;
            while ((line = in.readLine()) != null) {
                result.append(line);
            }
            /**
             * 返回結果示例
             */
            System.err.println("result:" + result);
            JSONObject jsonObject = new JSONObject(result.toString());
            return jsonObject.getString("access_token");
        } catch (Exception e) {
            System.err.printf("獲取token失敗！");
            e.printStackTrace(System.err);
        }
        return null;
    }

    public static void main(String[] args) {
        getAuth();
    }

}
 

3、編寫將圖片轉化成base64後再轉化成urlencode的工具類

package search;

/**
 * Created by within on 2018/10/9.
 */
import sun.misc.BASE64Encoder;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;

/**
 * 圖片轉化base64後再UrlEncode結果
 * @Author : within
 */

class BaseImg64 {
    /**
     * 將一張本地圖片轉化成Base64字串
     * @param imgPath 本地圖片地址
     * @return 圖片轉化base64後再UrlEncode結果
     */
    public static String getImageStrFromPath(String imgPath) {
        InputStream in;
        byte[] data = null;
        // 讀取圖片位元組陣列
        try {
            in = new FileInputStream(imgPath);
            data = new byte[in.available()];
            in.read(data);
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 對位元組陣列Base64編碼
        BASE64Encoder encoder = new BASE64Encoder();
        // 返回Base64編碼過再URLEncode的位元組陣列字串
        return URLEncoder.encode(encoder.encode(data));
    }
}
 

 4、編寫呼叫百度API介面的方法，獲取識別結果

package search;

/**
 * Created by within on 2018/10/9.
 */
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

/**
 * 影象文字識別
 *
 * @Author : within
 */

public class check {
    private static final String POST_URL = "https://aip.baidubce.com/rest/2.0/ocr/v1/general_basic?access_token=" + AuthService.getAuth();

    /**
     * 識別本地圖片的文字
     *
     * @param path 本地圖片地址
     * @return 識別結果，為json格式
     * @throws URISyntaxException URI開啟異常
     * @throws IOException        io流異常
     */
    public static String checkFile(String path) throws URISyntaxException, IOException {
        File file = new File(path);
        if (!file.exists()) {
            throw new NullPointerException("圖片不存在");
        }
        String image = BaseImg64.getImageStrFromPath(path);
        String param = "image=" + image;
        return post(param);
    }

    /**
     * @param url 圖片url
     * @return 識別結果，為json格式
     */
    public static String checkUrl(String url) throws IOException, URISyntaxException {
        String param = "url=" + url;
        return post(param);
    }

    /**
     * 通過傳遞引數：url和image進行文字識別
     *
     * @param param 區分是url還是image識別
     * @return 識別結果
     * @throws URISyntaxException URI開啟異常
     * @throws IOException        IO流異常
     */
    private static String post(String param) throws URISyntaxException, IOException {
        //開始搭建post請求
        HttpClient httpClient = new DefaultHttpClient();
        HttpPost post = new HttpPost();
        URI url = new URI(POST_URL);
        post.setURI(url);
        //設定請求頭，請求頭必須為application/x-www-form-urlencoded，因為是傳遞一個很長的字串，不能分段傳送
        post.setHeader("Content-Type", "application/x-www-form-urlencoded");
        StringEntity entity = new StringEntity(param);
        post.setEntity(entity);
        HttpResponse response = httpClient.execute(post);
        System.out.println(response.toString());
        if (response.getStatusLine().getStatusCode() == 200) {
            String str;
            try {
                /*讀取伺服器返回過來的json字串資料*/
                str = EntityUtils.toString(response.getEntity());
                System.out.println(str);
                return str;
            } catch (Exception e) {
                e.printStackTrace();
                return null;
            }
        }
        return null;
    }

    public static void main(String[] args) {
        String path = "D:\\ddd\\b.jpg";
        try {
            long now = System.currentTimeMillis();
            checkFile(path);
            checkUrl("https://gss3.bdstatic.com/-Po3dSag_xI4khGkpoWK1HF6hhy/baike/c0%3Dbaike80%2C5%2C5%2C80%2C26/sign=08c05c0e8444ebf8797c6c6db890bc4f/fc1f4134970a304e46bfc5f7d2c8a786c9175c19.jpg");
            System.out.println("耗時：" + (System.currentTimeMillis() - now) / 1000 + "s");
        } catch (URISyntaxException | IOException e) {
            e.printStackTrace();
        }
    }
}

5、結果對比：

 HTTP/1.1 200 OK [Appid: 14374247, Connection: keep-alive, Content-Type: application/json, Date: Tue, 09 Oct 2018 02:33:39 GMT, P3p: CP=" OTI DSP COR IVA OUR IND COM ", P3p: CP=" OTI DSP COR IVA OUR IND COM ", P3p: CP=" OTI DSP COR IVA OUR IND COM ", Server: Apache, Set-Cookie: BAIDUID=85ED51BC904917BC65233AB4200AD43E:FG=1; expires=Wed, 09-Oct-19 02:33:39 GMT; max-age=31536000; path=/; domain=.baidu.com; version=1, Set-Cookie: BAIDUID=90083625BD94E791CA9F2204797662B5:FG=1; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2145916555; path=/; domain=.baidu.com; version=1, Set-Cookie: BAIDUID=08654EC80A32DEBA38E50B18A85EDC5D:FG=1; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2145916555; path=/; domain=.baidu.com; version=1, Tracecode: 20198605130249338634100910, Vary: Accept-Encoding, Vary: Accept-Encoding, Content-Length: 317] [email protected]
{"log_id": 597441327730160468, "words_result_num": 5, "words_result": [{"words": "你想過普通的生活就會遇到普通的挫折"}, {"words": "你想過上最好的生活②"}, {"words": "就一定會遇上最強的傷害"}, {"words": "這世界很公平"}, {"words": "你想要最好就一定會給你最痛"}]}
十月 09, 2018 10:33:39 上午 org.apache.http.client.protocol.ResponseProcessCookies processCookies