com.google.web.bindery.requestfactory.vm.impl.OperationKey.java Source code

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Here is the source code for com.google.web.bindery.requestfactory.vm.impl.OperationKey.java

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/*
 * Copyright 2011 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.web.bindery.requestfactory.vm.impl;

import com.google.gwt.dev.asm.Type;
import com.google.gwt.dev.asm.commons.Method;
import com.google.gwt.dev.util.StringKey;
import com.google.gwt.user.server.Base64Utils;

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

/**
 * Utility class for encoding RequestFactory operation ids.
 */
public class OperationKey extends StringKey {
    /**
     * The expected length of values returned from {@link #hash(String)}.
     */
    public static final int HASH_LENGTH = 28;

    static {
        assert HASH_LENGTH == hash("").length();
    }

    /**
     * Compute a base64-encoded SHA1 hash of the input string's UTF8
     * representation. The result is a {@value #HASH_LENGTH}-character sequence.
     */
    public static String hash(String raw) {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA1");
            byte[] data = md.digest(raw.getBytes("UTF-8"));
            return Base64Utils.toBase64(data);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("No MD5 algorithm", e);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("No UTF-8", e);
        }
    }

    private static String key(String requestContextBinaryName, String methodName, String descriptor) {
        Method m = new Method(methodName, Type.VOID_TYPE, Type.getArgumentTypes(descriptor));
        String raw = requestContextBinaryName + "::" + methodName + m.getDescriptor();
        return raw.length() >= HASH_LENGTH ? hash(raw) : raw;
    }

    public OperationKey(String encoded) {
        super(encoded);
        assert encoded.length() == HASH_LENGTH : "Expecting only " + HASH_LENGTH + " characters, received "
                + encoded.length();
    }

    public OperationKey(String requestContextBinaryName, String methodName, String descriptor) {
        super(key(requestContextBinaryName, methodName, descriptor));
    }
}