这就是一个工具类，直接上代码了：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87

import java.security.MessageDigest;

import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.Signature;
import android.util.Log;

/**
 * 签名工具类
 * 
 * 
 */
public class SignUtil {
	/**
	 * 获取对应包名的应用的签名串
	 * 
	 * @param context
	 * @param paramString
	 *            应用程序包名
	 * @return
	 */
	public static String getSign(Context context, String paramString) {
		if (context == null) {
			throw new IllegalAccessError("Context is null!!!");
		}
		Signature[] arrayOfSignature = getRawSignature(context, paramString);
		if ((arrayOfSignature == null) || (arrayOfSignature.length == 0)) {
			Log.d("SIGN", "signs is null");
			return null;
		}
		int i = arrayOfSignature.length;
		if (i > 0) {
			return getMessageDigest(arrayOfSignature[0].toByteArray());
		}
		return null;
	}

	private static Signature[] getRawSignature(Context paramContext,
			String paramString) {
		if ((paramString == null) || (paramString.length() == 0)) {
			Log.d("SIGN", "getSignature, packageName is null");
			return null;
		}
		PackageManager localPackageManager = paramContext.getPackageManager();
		PackageInfo localPackageInfo;
		try {
			localPackageInfo = localPackageManager.getPackageInfo(paramString,
					64);
			if (localPackageInfo == null) {
				Log.d("SIGN", "info is null, packageName = " + paramString);
				return null;
			}
		} catch (PackageManager.NameNotFoundException localNameNotFoundException) {
			Log.d("SIGN", "NameNotFoundException");
			return null;
		}
		return localPackageInfo.signatures;
	}

	private static final String getMessageDigest(byte[] paramArrayOfByte) {
		char[] arrayOfChar1 = { 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 97, 98,
				99, 100, 101, 102 };
		try {
			MessageDigest localMessageDigest = MessageDigest.getInstance("MD5");
			localMessageDigest.update(paramArrayOfByte);
			byte[] arrayOfByte = localMessageDigest.digest();
			int i = arrayOfByte.length;
			char[] arrayOfChar2 = new char[i * 2];
			int j = 0;
			int k = 0;
			while (true) {
				if (j >= i)
					return new String(arrayOfChar2);
				int m = arrayOfByte[j];
				int n = k + 1;
				arrayOfChar2[k] = arrayOfChar1[(0xF & m >>> 4)];
				k = n + 1;
				arrayOfChar2[n] = arrayOfChar1[(m & 0xF)];
				j++;
			}
		} catch (Exception localException) {
		}
		return null;
	}
}