xmloutputarchive.java

hadoop:Nutch集群平台

/**
 * Copyright 2005 The Apache Software Foundation
 *
 * 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 org.apache.hadoop.record;

import java.io.IOException;
import java.io.ByteArrayOutputStream;
import java.util.TreeMap;
import java.util.ArrayList;
import java.io.PrintStream;
import java.io.OutputStream;
import java.util.Stack;
import org.apache.hadoop.io.Text;

/**
 *
 * @author Milind Bhandarkar
 */
class XmlOutputArchive implements OutputArchive {

    private PrintStream stream;
    
    private int indent = 0;
    
    private Stack compoundStack;
    
    private void putIndent() {
        StringBuffer sb = new StringBuffer("");
        for (int idx = 0; idx < indent; idx++) {
            sb.append("  ");
        }
        stream.print(sb.toString());
    }
    
    private void addIndent() {
        indent++;
    }
    
    private void closeIndent() {
        indent--;
    }
    
    private void printBeginEnvelope(String tag) {
        if (!compoundStack.empty()) {
            String s = (String) compoundStack.peek();
            if ("struct".equals(s)) {
                putIndent();
                stream.print("<member>\n");
                addIndent();
                putIndent();
                stream.print("<name>"+tag+"</name>\n");
                putIndent();
                stream.print("<value>");
            } else if ("vector".equals(s)) {
                stream.print("<value>");
            } else if ("map".equals(s)) {
                stream.print("<value>");
            }
        } else {
            stream.print("<value>");
        }
    }
    
    private void printEndEnvelope(String tag) {
        if (!compoundStack.empty()) {
            String s = (String) compoundStack.peek();
            if ("struct".equals(s)) {
                stream.print("</value>\n");
                closeIndent();
                putIndent();
                stream.print("</member>\n");
            } else if ("vector".equals(s)) {
                stream.print("</value>\n");
            } else if ("map".equals(s)) {
                stream.print("</value>\n");
            }
        } else {
            stream.print("</value>\n");
        }
    }
    
    private void insideVector(String tag) {
        printBeginEnvelope(tag);
        compoundStack.push("vector");
    }
    
    private void outsideVector(String tag) throws IOException {
        String s = (String) compoundStack.pop();
        if (!"vector".equals(s)) {
            throw new IOException("Error serializing vector.");
        }
        printEndEnvelope(tag);
    }
    
    private void insideMap(String tag) {
        printBeginEnvelope(tag);
        compoundStack.push("map");
    }
    
    private void outsideMap(String tag) throws IOException {
        String s = (String) compoundStack.pop();
        if (!"map".equals(s)) {
            throw new IOException("Error serializing map.");
        }
        printEndEnvelope(tag);
    }
    
    private void insideRecord(String tag) {
        printBeginEnvelope(tag);
        compoundStack.push("struct");
    }
    
    private void outsideRecord(String tag) throws IOException {
        String s = (String) compoundStack.pop();
        if (!"struct".equals(s)) {
            throw new IOException("Error serializing record.");
        }
        printEndEnvelope(tag);
    }
    
    static XmlOutputArchive getArchive(OutputStream strm) {
        return new XmlOutputArchive(strm);
    }
    
    /** Creates a new instance of XmlOutputArchive */
    public XmlOutputArchive(OutputStream out) {
        stream = new PrintStream(out);
        compoundStack = new Stack();
    }
    
    public void writeByte(byte b, String tag) throws IOException {
        printBeginEnvelope(tag);
        stream.print("<ex:i1>");
        stream.print(Byte.toString(b));
        stream.print("</ex:i1>");
        printEndEnvelope(tag);
    }
    
    public void writeBool(boolean b, String tag) throws IOException {
        printBeginEnvelope(tag);
        stream.print("<boolean>");
        stream.print(b ? "1" : "0");
        stream.print("</boolean>");
        printEndEnvelope(tag);
    }
    
    public void writeInt(int i, String tag) throws IOException {
        printBeginEnvelope(tag);
        stream.print("<i4>");
        stream.print(Integer.toString(i));
        stream.print("</i4>");
        printEndEnvelope(tag);
    }
    
    public void writeLong(long l, String tag) throws IOException {
        printBeginEnvelope(tag);
        stream.print("<ex:i8>");
        stream.print(Long.toString(l));
        stream.print("</ex:i8>");
        printEndEnvelope(tag);
    }
    
    public void writeFloat(float f, String tag) throws IOException {
        printBeginEnvelope(tag);
        stream.print("<ex:float>");
        stream.print(Float.toString(f));
        stream.print("</ex:float>");
        printEndEnvelope(tag);
    }
    
    public void writeDouble(double d, String tag) throws IOException {
        printBeginEnvelope(tag);
        stream.print("<double>");
        stream.print(Double.toString(d));
        stream.print("</double>");
        printEndEnvelope(tag);
    }
    
    public void writeString(Text s, String tag) throws IOException {
        printBeginEnvelope(tag);
        stream.print("<string>");
        stream.print(Utils.toXMLString(s));
        stream.print("</string>");
        printEndEnvelope(tag);
    }
    
    public void writeBuffer(ByteArrayOutputStream buf, String tag)
    throws IOException {
        printBeginEnvelope(tag);
        stream.print("<string>");
        stream.print(Utils.toXMLBuffer(buf));
        stream.print("</string>");
        printEndEnvelope(tag);
    }
    
    public void writeRecord(Record r, String tag) throws IOException {
        r.serialize(this, tag);
    }
    
    public void startRecord(Record r, String tag) throws IOException {
        insideRecord(tag);
        stream.print("<struct>\n");
        addIndent();
    }
    
    public void endRecord(Record r, String tag) throws IOException {
        closeIndent();
        putIndent();
        stream.print("</struct>");
        outsideRecord(tag);
    }
    
    public void startVector(ArrayList v, String tag) throws IOException {
        insideVector(tag);
        stream.print("<array>\n");
        addIndent();
    }
    
    public void endVector(ArrayList v, String tag) throws IOException {
        closeIndent();
        putIndent();
        stream.print("</array>");
        outsideVector(tag);
    }
    
    public void startMap(TreeMap v, String tag) throws IOException {
        insideMap(tag);
        stream.print("<array>\n");
        addIndent();
    }
    
    public void endMap(TreeMap v, String tag) throws IOException {
        closeIndent();
        putIndent();
        stream.print("</array>");
        outsideMap(tag);
    }

}