百度具体文档中心：http://ai.baidu.com/docs#/OCR-API/e1bd77f3
具体的注册、创建应用可以从文档中心的新手指南开始看下，文档都写的很清楚明白。
直接上代码了：
1、获取 access_token：
package com.baidu;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.List;
import java.util.Map;
import com.alibaba.fastjson.JSONObject;
public class AccessToken {
/**
* 获取API访问token
* 该token有一定的有效期，需要自行管理，当失效时需重新获取.
* @param ak - 百度云官网获取的 API Key
* @param sk - 百度云官网获取的 Securet Key
* @return assess_token 示例：
* "24.460da4889caad24cccdb1fea17221975.2592000.1491995545.282335-1234567"
*/
public static String getAuth(String ak, String sk) {
// 获取token地址
String authHost = "https://aip.baidubce.com/oauth/2.0/token?";
String getAccessTokenUrl = authHost
// 1. grant_type为固定参数
+ "grant_type=client_credentials"
// 2. 官网获取的 API Key
+ "&client_id=" + ak
// 3. 官网获取的 Secret Key
+ "&client_secret=" + sk;
try {
URL realUrl = new URL(getAccessTokenUrl);
// 打开和URL之间的连接
HttpURLConnection connection = (HttpURLConnection) realUrl.openConnection();
connection.setRequestMethod("GET");
connection.connect();
// 获取所有响应头字段
Map<String, List<String>> map = connection.getHeaderFields();
// 遍历所有的响应头字段
for (String key : map.keySet()) {
System.err.println(key + "--->" + map.get(key));
}
// 定义 BufferedReader输入流来读取URL的响应
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String result = "";
String line;
while ((line = in.readLine()) != null) {
result += line;
}
/**
* 返回结果示例
*/
System.out.println("result:" + result);
JSONObject jsonObject = JSONObject.parseObject(result);
String access_token = jsonObject.getString("access_token");
return access_token;
} catch (Exception e) {
System.err.printf("获取token失败！");
e.printStackTrace(System.err);
}
return null;
}
public static void main(String[] args) {
String ac = getAuth("rYlaI2pjuU2g1lMRAyy5","UQECARmHtwmpU1X5Do8yyejs980");
System.out.println(ac);
}
}
2、编写将图片转化成base64后再转化成urlencode的工具类
如果 sun.misc.BASE64Encoder 找不到包，
右击工程，点击properties, 将已配置的Libraries jre文件移除，再点击AddLibrary，选择jre system Library，加入jre，点击---next,最后finish 完成即可
可以看下这篇文章：https://blog.csdn.net/wang9258/article/details/17764985
package com.baidu;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import sun.misc.BASE64Encoder;
public class BaseImg64 {
/** * 将一张本地图片转化成Base64字符串 *
* @param imgPath 本地图片地址
* *
* @return 图片转化base64后再UrlEncode结果
* */
public static String getImageStrFromPath(String imgPath) {
InputStream in;
byte[] data = null;
// 读取图片字节数组
try {
in = new FileInputStream(imgPath);
data = new byte[in.available()];
in.read(data); in.close();
} catch (IOException e) {
e.printStackTrace(); }
// 对字节数组Base64编码
BASE64Encoder encoder = new BASE64Encoder();
// 返回Base64编码过再URLEncode的字节数组字符串
try {
return URLEncoder.encode(encoder.encode(data),"UTF-8");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
3、编写调用百度API接口的方法，获取识别结果
package com.baidu;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
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.HttpClientBuilder;
import org.apache.http.util.EntityUtils;
import com.alibaba.fastjson.JSONObject;
public class BaiduOCR {
private static final String POST_URL = "https://aip.baidubce.com/rest/2.0/ocr/v1/general_basic?access_token=accessToken";
/** * 识别本地图片的文字 * *
* @param path 本地图片地址 *
* @return 识别结果，为json格式 *
* @throws URISyntaxException URI打开异常 *
* @throws IOException io流异常 *
**/
public static String checkFile(String path) throws URISyntaxException, IOException {
File file = new File(path);
if (!file.exists()) {
throw new NullPointerException("图片不存在");
}
String image = BaseImg64.getImageStrFromPath(path);
String param = "image=" + image;
return generalBasic(param);
}
/** * @param url 图片url *
* @return 识别结果，为json格式
* */
public static String checkUrl(String url) throws IOException, URISyntaxException {
String param = "url=" + url;
return generalBasic(param);
}
/**
* 通用文字识别
* 通过传递参数：url和image进行文字识别 * *
@param param 区分是url还是image识别 *
@return 识别结果 *
@throws URISyntaxException URI打开异常 *
@throws IOException IO流异常
*/
private static String generalBasic(String param) throws URISyntaxException, IOException {
//开始搭建post请求
HttpClient httpClient = HttpClientBuilder.create().build();
HttpPost post = new HttpPost();
String postUrl = POST_URL.replace("accessToken", "24.67ad73dcf15b5a38437d.2592000.1548398741.282335");
URI url = new URI(postUrl);
post.setURI(url);
//设置请求头，请求头必须为application/x-www-form-urlencoded，因为是传递一个很长的字符串，不能分段发送
post.setHeader("Content-Type", "application/x-www-form-urlencoded");
StringEntity entity = new StringEntity(param);
post.setEntity(entity);
HttpResponse response = httpClient.execute(post);
if (response.getStatusLine().getStatusCode() == 200) {
String str;
try {
/*读取服务器返回过来的json字符串数据*/
str = EntityUtils.toString(response.getEntity());
return str;
} catch (Exception e) {
e.printStackTrace();
}
}
return null;
}
public static void main(String[] args) {
String path = "g:\\pic\\4.jpg";
String result;
try {
long now = System.currentTimeMillis();
// result = checkFile(path);
result = checkUrl("https://gss3.bdstatic.com/-Po3dSag_xI4khGkpoWK1HF6hhy/baike/c0%3Dbaike80%2C5%2C5%2C80%2C26/sign=08c05c0e8444ebf8797c6c6db890bc4f/fc1f4134970a304e46bfc5f7d2c8a786c9175c19.jpg");
System.out.println(JSONObject.parse(result));
System.out.println("耗时：" + (System.currentTimeMillis() - now) / 1000 + "s");
} catch (URISyntaxException | IOException e) {
e.printStackTrace();
}
}
}
百度的文档中心还有很多接口，写的很好。