站长工具: 用java 程序得到google的pagerank(PR)

很多做网站的兄弟都很关心自己网站的PR值,虽然google已经停止PR的排名等,但事实上PR每隔一段时间还是在更新,PR的本意是用来衡量一个网站页面质量的高低,但后来有人恶意的刷PR,或者用别的方法偷取人家网站的PR。写程序的人,总想知道PR是怎么算出来的,其实google采用的算法也是公开的。下面就用java来获取自己这个网站的PR值。

根据google 的工具条,可以看到请求的方式:
http://toolbarqueries.google.com/tbr?client=navclient-auto&hl=en&ch=6236440745
&ie=UTF-8&oe=UTF-8&features=Rank&q=info:yihaomen.com

这里面最重要的就是计算ch=? 这个参数

程序代码 程序代码

package pr.google.test;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;

public class GoogleSeoHelper {

  public static void main(String[] args) {
    GoogleSeoHelper obj = new GoogleSeoHelper();
    System.out.println(obj.getPR("yihaomen.com"));
  }

  public int getPR(String domain) {
    String result = "";
    JenkinsHash jenkinsHash = new JenkinsHash();
    long hash = jenkinsHash.hash(("info:" + domain).getBytes());
    //Append a 6 in front of the hashing value.
    String url = "http://toolbarqueries.google.com/tbr?client=navclient-auto&hl=en&"
       + "ch=6" + hash + "&ie=UTF-8&oe=UTF-8&features=Rank&q=info:" + domain;

    System.out.println("Sending request to : " + url);

    try {
        URLConnection conn = new URL(url).openConnection();

        BufferedReader br = new BufferedReader(new InputStreamReader(
            conn.getInputStream()));

        String input;
        while ((input = br.readLine()) != null) {
            // What Google returned? Example : Rank_1:1:9, PR = 9
            System.out.println(input);
            result = input.substring(input.lastIndexOf(":") + 1);
        }

    } catch (Exception e) {
        System.out.println(e.getMessage());
    }

    if ("".equals(result)) {
        return 0;
    } else {
        return Integer.valueOf(result);
    }

  }

}


还需要一个辅助类,这个是开源的,google也是用的它.

程序代码 程序代码

package pr.google.test;

/**
* Hash algorithm by Bob Jenkins, 1996.
*
* You may use this code any way you wish, private, educational, or commercial.
* It's free. See: http://burtleburtle.net/bob/hash/doobs.html
*
*/
public class JenkinsHash {

    // max value to limit it to 4 bytes
    private static final long MAX_VALUE = 0xFFFFFFFFL;

    // internal variables used in the various calculations
    long a;
    long b;
    long c;

    /**
     * Convert a byte into a long value without making it negative.
     */
    private long byteToLong(byte b) {
        long val = b & 0x7F;
        if ((b & 0x80) != 0) {
            val += 128;
        }
        return val;
    }

    /**
     * Do addition and turn into 4 bytes.
     */
    private long add(long val, long add) {
        return (val + add) & MAX_VALUE;
    }

    /**
     * Do subtraction and turn into 4 bytes.
     */
    private long subtract(long val, long subtract) {
        return (val - subtract) & MAX_VALUE;
    }

    /**
     * Left shift val by shift bits and turn in 4 bytes.
     */
    private long xor(long val, long xor) {
        return (val ^ xor) & MAX_VALUE;
    }

    /**
     * Left shift val by shift bits. Cut down to 4 bytes.
     */
    private long leftShift(long val, int shift) {
        return (val << shift) & MAX_VALUE;
    }

    /**
     * Convert 4 bytes from the buffer at offset into a long value.
     */
    private long fourByteToLong(byte[] bytes, int offset) {
        return (byteToLong(bytes[offset + 0])
        + (byteToLong(bytes[offset + 1]) << 8)
        + (byteToLong(bytes[offset + 2]) << 16) + (byteToLong(bytes[offset + 3]) << 24));
    }

    /**
     * Mix up the values in the hash function.
     */
    private void hashMix() {
        a = subtract(a, b);
        a = subtract(a, c);
        a = xor(a, c >> 13);
        b = subtract(b, c);
        b = subtract(b, a);
        b = xor(b, leftShift(a, 8));
        c = subtract(c, a);
        c = subtract(c, b);
        c = xor(c, (b >> 13));
        a = subtract(a, b);
        a = subtract(a, c);
        a = xor(a, (c >> 12));
        b = subtract(b, c);
        b = subtract(b, a);
        b = xor(b, leftShift(a, 16));
        c = subtract(c, a);
        c = subtract(c, b);
        c = xor(c, (b >> 5));
        a = subtract(a, b);
        a = subtract(a, c);
        a = xor(a, (c >> 3));
        b = subtract(b, c);
        b = subtract(b, a);
        b = xor(b, leftShift(a, 10));
        c = subtract(c, a);
        c = subtract(c, b);
        c = xor(c, (b >> 15));
    }

    /**
     * Hash a variable-length key into a 32-bit value. Every bit of the key
     * affects every bit of the return value. Every 1-bit and 2-bit delta
     * achieves avalanche. The best hash table sizes are powers of 2.
     *
     * @param buffer
     *            Byte array that we are hashing on.
     * @param initialValue
     *            Initial value of the hash if we are continuing from a previous
     *            run. 0 if none.
     * @return Hash value for the buffer.
     */
    public long hash(byte[] buffer, long initialValue) {
        int len, pos;

        // set up the internal state
        // the golden ratio; an arbitrary value
        a = 0x09e3779b9L;
        // the golden ratio; an arbitrary value
        b = 0x09e3779b9L;
        // the previous hash value

        //c = initialValue;
        c = 0x0E6359A60L;

        // handle most of the key
        pos = 0;
        for (len = buffer.length; len >= 12; len -= 12) {
            a = add(a, fourByteToLong(buffer, pos));
            b = add(b, fourByteToLong(buffer, pos + 4));
            c = add(c, fourByteToLong(buffer, pos + 8));
            hashMix();
            pos += 12;
        }

        c += buffer.length;

        // all the case statements fall through to the next on purpose
        switch (len) {
        case 11:
            c = add(c, leftShift(byteToLong(buffer[pos + 10]), 24));
        case 10:
            c = add(c, leftShift(byteToLong(buffer[pos + 9]), 16));
        case 9:
            c = add(c, leftShift(byteToLong(buffer[pos + 8]), 8));
            // the first byte of c is reserved for the length
        case 8:
            b = add(b, leftShift(byteToLong(buffer[pos + 7]), 24));
        case 7:
            b = add(b, leftShift(byteToLong(buffer[pos + 6]), 16));
        case 6:
            b = add(b, leftShift(byteToLong(buffer[pos + 5]), 8));
        case 5:
            b = add(b, byteToLong(buffer[pos + 4]));
        case 4:
            a = add(a, leftShift(byteToLong(buffer[pos + 3]), 24));
        case 3:
            a = add(a, leftShift(byteToLong(buffer[pos + 2]), 16));
        case 2:
            a = add(a, leftShift(byteToLong(buffer[pos + 1]), 8));
        case 1:
            a = add(a, byteToLong(buffer[pos + 0]));
            // case 0: nothing left to add
        }
        hashMix();

        return c;
    }

    /**
     * See hash(byte[] buffer, long initialValue)
     *
     * @param buffer
     *            Byte array that we are hashing on.
     * @return Hash value for the buffer.
     */
    public long hash(byte[] buffer) {
        return hash(buffer, 0);
    }
}


在运行的时候,你可以得到如下结果:
程序代码 程序代码

Sending request to : http://toolbarqueries.google.com/tbr?client=navclient-auto&hl=en&ch=61903917350&ie=UTF-8&oe=UTF-8&features=Rank&q=info:yihaomen.com
Rank_1:1:1
1

由此可以 看出,yihaomen.com 的PR 值是1.看来权重不够呀,所以pr很低。

除非申明,文章均为一号门原创,转载请注明本文地址,谢谢!
[本日志由 轻舞肥羊 于 2013-01-28 09:46 PM 编辑]
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