domecho.java

精通Java核心技术的随书源代码

// ==================== Program Discription ==========================
// 程序名称：示例21-1 : DOMEcho.java
// 程序目的：使用JAXP输出DOM树
// ==============================================================
import javax.xml.parsers.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
import org.w3c.dom.*;
import java.io.*;

public class DOMEcho {
    static final String outputEncoding = "UTF-8";
    private PrintWriter out;
    private int indent = 0;
    private final String basicIndent = "  ";
    DOMEcho(PrintWriter out) {
        this.out = out;
    }
    
    // output the common attributes of DOM2 nodes 
    private void printlnCommon(Node n) {
        out.print(" nodeName=\"" + n.getNodeName() + "\"");
        String val = n.getNamespaceURI();
        if (val != null) {
            out.print(" uri=\"" + val + "\"");
        }
        val = n.getPrefix();
        if (val != null) {
            out.print(" pre=\"" + val + "\"");
        }
        val = n.getLocalName();
        if (val != null) {
            out.print(" local=\"" + val + "\"");
        }
        val = n.getNodeValue();
        if (val != null) {
            out.print(" nodeValue=");
            if (val.trim().equals("")) {
                // Whitespace
                out.print("[WS]");
            } else {
                out.print("\"" + n.getNodeValue() + "\"");
            }
        }
        out.println();
    }
    
    private void outputIndentation() {
        for (int i = 0; i < indent; i++) {
            out.print(basicIndent);
        }
    }
    
    // output the DOM tree nodes iteratelly
    private void echo(Node n) {
        outputIndentation();
        int type = n.getNodeType();
        switch (type) {
        case Node.ATTRIBUTE_NODE:
            out.print("ATTR:");
            printlnCommon(n);
            break;
        case Node.CDATA_SECTION_NODE:
            out.print("CDATA:");
            printlnCommon(n);
            break;
        case Node.COMMENT_NODE:
            out.print("COMM:");
            printlnCommon(n);
            break;
        case Node.DOCUMENT_FRAGMENT_NODE:
            out.print("DOC_FRAG:");
            printlnCommon(n);
            break;
        case Node.DOCUMENT_NODE:
            out.print("DOC:");
            printlnCommon(n);
            break;
        case Node.DOCUMENT_TYPE_NODE:
            out.print("DOC_TYPE:");
            printlnCommon(n);
            // Print entities if any
            NamedNodeMap nodeMap = ((DocumentType)n).getEntities();
            indent += 2;
            for (int i = 0; i < nodeMap.getLength(); i++) {
                Entity entity = (Entity)nodeMap.item(i);
                echo(entity);
            }
            indent -= 2;
            break;
        case Node.ELEMENT_NODE:
            out.print("ELEM:");
            printlnCommon(n);
            // output all attributes of current node
            NamedNodeMap atts = n.getAttributes();
            indent += 2;
            for (int i = 0; i < atts.getLength(); i++) {
                Node att = atts.item(i);
                echo(att);
            }
            indent -= 2;
            break;
        case Node.ENTITY_NODE:
            out.print("ENT:");
            printlnCommon(n);
            break;
        case Node.ENTITY_REFERENCE_NODE:
            out.print("ENT_REF:");
            printlnCommon(n);
            break;
        case Node.NOTATION_NODE:
            out.print("NOTATION:");
            printlnCommon(n);
            break;
        case Node.PROCESSING_INSTRUCTION_NODE:
            out.print("PROC_INST:");
            printlnCommon(n);
            break;
        case Node.TEXT_NODE:
            out.print("TEXT:");
            printlnCommon(n);
            break;
        default:
            out.print("UNSUPPORTED NODE: " + type);
            printlnCommon(n);
            break;
        }
        // output all subnodes
        indent++;
        for (Node child = n.getFirstChild(); child != null;
             child = child.getNextSibling()) {
            echo(child);
        }
        indent--;
    }

    private static void usage() {
        System.err.println("Usage: DOMEcho [-opts] <filename>");
        System.err.println("       -v = validation");
        System.err.println("       -ws = do not create whitespace nodes");
        System.err.println("       -co[mments] = do not create comment nodes");
        System.err.println("       -cd[ata] = put CDATA into Text nodes");
        System.err.println("       -e[ntity-ref] = create EntityReference nodes");
        System.exit(1);
    }

    public static void main(String[] args) throws Exception {
        String filename = null;
        boolean validation = false;
        boolean ignoreWhitespace = false;
        boolean ignoreComments = false;
        boolean putCDATAIntoText = false;
        boolean createEntityRefs = false;
        for (int i = 0; i < args.length; i++) {
            if (args[i].equals("-v")) {
                validation = true;
            } else if (args[i].equals("-ws")) {
                ignoreWhitespace = true;
            } else if (args[i].startsWith("-co")) {
                ignoreComments = true;
            } else if (args[i].startsWith("-cd")) {
                putCDATAIntoText = true;
            } else if (args[i].startsWith("-e")) {
                createEntityRefs = true;
            } else {
                filename = args[i];
                // Must be last arg
                if (i != args.length - 1) {
                    usage();
                }
            }
        }
        if (filename == null) {
            usage();
        }

        // create DocumentBuilderFactory
        DocumentBuilderFactory dbf =
            DocumentBuilderFactory.newInstance();
        dbf.setNamespaceAware(true);
        dbf.setValidating(validation);
        dbf.setIgnoringComments(ignoreComments);
        dbf.setIgnoringElementContentWhitespace(ignoreWhitespace);
        dbf.setCoalescing(putCDATAIntoText);
        dbf.setExpandEntityReferences(!createEntityRefs);

        // create a DocumentBuilder instance
        DocumentBuilder db = null;
        try {
            db = dbf.newDocumentBuilder();
        } catch (ParserConfigurationException pce) {
            System.err.println(pce);
            System.exit(1);
        }
        
        OutputStreamWriter errorWriter =
            new OutputStreamWriter(System.err, outputEncoding);
        db.setErrorHandler(
            new MyErrorHandler(new PrintWriter(errorWriter, true)));
       
        Document doc = null;
        try {
            doc = db.parse(new File(filename));
        } catch (SAXException se) {
            System.err.println(se.getMessage());
            System.exit(1);
        } catch (IOException ioe) {
            System.err.println(ioe);
            System.exit(1);
        }

        // output the DOM tree
        OutputStreamWriter outWriter =
            new OutputStreamWriter(System.out, outputEncoding);
        new DOMEcho(new PrintWriter(outWriter, true)).echo(doc);
    }

    // error handling
    private static class MyErrorHandler implements ErrorHandler {
        private PrintWriter out;
        MyErrorHandler(PrintWriter out) {
            this.out = out;
        }
        
        private String getParseExceptionInfo(SAXParseException spe) {
            String systemId = spe.getSystemId();
            if (systemId == null) {
                systemId = "null";
            }
            String info = "URI=" + systemId +
                " Line=" + spe.getLineNumber() +
                ": " + spe.getMessage();
            return info;
        }
        
        public void warning(SAXParseException spe) throws SAXException {
            out.println("Warning: " + getParseExceptionInfo(spe));
        }
        public void error(SAXParseException spe) throws SAXException {
            String message = "Error: " + getParseExceptionInfo(spe);
            throw new SAXException(message);
        }
        public void fatalError(SAXParseException spe) throws SAXException {
            String message = "Fatal Error: " + getParseExceptionInfo(spe);
            throw new SAXException(message);
        }
    }
}