从来没有接触过java加密，近期在工作中遇到java加密的问题，由于对java加密不是很清楚，在写程序的过程中挺纠结的，最后终于搞定，现在把示例程序的代码贴上来，供大家看看。有什么问题请尽管拍砖。

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;
/**
 * 对字符串进行加密和解密
 * @author
 *
 */
public class Encryptions {
    /**
     * 对字符串进行加密，并返回加密后的字符串。<br>
     * 加密注意事项：<br>
     *    如果用ECB保密模式，iv字符串必须为null，否则会造成加密出错的问题。<br>
     * @param target 要加密的字符串
     * @param keyString 密钥
     * @param algorithm 加密算法名称
     * @param mode 保密模式
     * @param padding 加密填充模式
     * @param iv 向量字符串
     * @return 加密后的字符串
     */
    public String encrypt(String target, String keyString, String algorithm, String mode, String padding, String iv) {
        SecretKeySpec keySpec = new SecretKeySpec(keyString.getBytes(), algorithm);
        String encryptStr = null;
        String algorithmStr = null;
                          
        if (mode != null && padding !=null && !mode.isEmpty() && !padding.isEmpty()) {
            StringBuilder algorithmBuilder = new StringBuilder(CommonConst.STTING_BUILDER_CAPACITY);
            algorithmBuilder.append(algorithm);
            algorithmBuilder.append(CommonConst.SLASH);
            algorithmBuilder.append(mode);
            algorithmBuilder.append(CommonConst.SLASH);
            algorithmBuilder.append(padding);
            algorithmStr = algorithmBuilder.toString();
        } else {
            algorithmStr = algorithm;
        }
                          
        try {
            Cipher cipher = Cipher.getInstance(algorithmStr);
            if (iv != null) {
                IvParameterSpec ivSpec = new IvParameterSpec(iv.getBytes());
                cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);             
            } else {
                cipher.init(Cipher.ENCRYPT_MODE, keySpec);             
            }
                              
            byte[] encryptBytes = cipher.doFinal(target.getBytes());
            encryptStr = Base64.encode(encryptBytes);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        } catch (InvalidAlgorithmParameterException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
                          
        return encryptStr;
    }
                      
    /**
     * 对加密后的字符串进行解密，并返回解密后的字符串<br>
     * 加密注意事项：<br>
     *    如果用ECB保密模式，iv字符串必须为null，否则会造成加密出错的问题。<br>
     * @param target 加密后的字符串（待解密字符串）
     * @param keyString 密钥
     * @param algorithm 加密算法名称
     * @param mode 保密模式
     * @param padding 填充模式
     * @param iv 向量字符串
     * @return 解密后的字符串
     */
    public String decrypt(String target, String keyString, String algorithm, String mode, String padding, String iv) {
        SecretKeySpec keySpec = new SecretKeySpec(keyString.getBytes(), algorithm);
        String encryptStr = null;
        String algorithmStr = null;
                          
        if (mode != null && padding !=null && !mode.isEmpty() && !padding.isEmpty()) {
            StringBuilder algorithmBuilder = new StringBuilder(CommonConst.STTING_BUILDER_CAPACITY);
            algorithmBuilder.append(algorithm);
            algorithmBuilder.append(CommonConst.SLASH);
            algorithmBuilder.append(mode);
            algorithmBuilder.append(CommonConst.SLASH);
            algorithmBuilder.append(padding);
            algorithmStr = algorithmBuilder.toString();
        } else {
            algorithmStr = algorithm;
        }
                          
        try {
            Cipher cipher = Cipher.getInstance(algorithmStr);
            if (iv != null) {
                IvParameterSpec ivSpec = new IvParameterSpec(iv.getBytes());
                cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
            } else {
                cipher.init(Cipher.DECRYPT_MODE, keySpec);
            }
                              
                              
            byte[] encryptBytes = cipher.doFinal(Base64.decode(target));
            encryptStr = new String(encryptBytes);
                              
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        } catch (InvalidAlgorithmParameterException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
                          
        return encryptStr;
    }

     最后的测试程序：

     

public static void main(String[] args) {
        Encryptions demo = new Encryptions();
        String before = "http://www.ostools.net/apidocs/apidoc?api=jdk_6u30";
        System.out.println("before:" + before);
        String after = demo.encrypt(before, "1234456iuyrdhfgd", "AES", "PCBC", "PKCS5Padding","1234456iuyrdhfgd");
        System.out.println("after:" + after);
        System.out.println("before:" + demo.decrypt(after, "1234456iuyrdhfgd", "AES", "PCBC", "PKCS5Padding", "1234456iuyrdhfgd"));
    }

    测试结果：

 

before:http://www.ostools.net/apidocs/apidoc?api=jdk_6u30
after:gn5zPbyJrX1aJzwqy7JltBgjFe0o39SvrGr6z1eyQ94Nm92U71N180UCMphJBToUXav97F+bJWObkk/IXaYldg==
before:http://www.ostools.net/apidocs/apidoc?api=jdk_6u30