2020101501

Secondary Namenode莫名其妙无法启动的原因找到。是端口被Eclipse占用的缘故。

同时，要求的文本编辑也编写完成。在设计的时候在编译原理的启发下做了个带有词法分析器+状态机(但是状态机对语法的分析有一些问题)的版本，模拟了一个简单的指令系统并且使得输入支持 代表换行、 代表制表符、\代表的等字符的转义。

源代码如下：

package konoha.pkg.p01;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Scanner;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FsUrlStreamHandlerFactory;
import org.apache.hadoop.fs.Path;

public class Type0TextEditor {
    private static Configuration conf;
    static {
        URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory());
    }

    public static void Config() {
        conf = new Configuration();
        conf.set("fs.defaultFS", "hdfs://localhost:9000");
        conf.set("fs.hdfs.impl", "org.apache.hadoop.hdfs.DistributedFileSystem");
    }

    public static boolean hasFile(String path) {
        try (FileSystem fs = FileSystem.get(conf)) {
            return fs.exists(new Path(path));
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }

    public static String readFile(String filePath) {
        InputStream in = null;
        String rtn = "";
        try {
            in = new URL(filePath).openStream();
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            String tmp = null;
            boolean flag = true;
            while ((tmp = br.readLine()) != null) {
                if (flag) {
                    flag = false;
                } else {
                    rtn = rtn + "
";
                }
                rtn = rtn + tmp;
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return rtn;
    }

    public static void writeFile(String content, String filePath) {
        BufferedWriter bw = null;
        try {
            FileSystem fs = FileSystem.get(conf);
            FSDataOutputStream fout = fs.create(new Path(filePath));
            bw = new BufferedWriter(new OutputStreamWriter(fout, "UTF-8"));
            bw.write(content);
            bw.newLine();
            bw.flush();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            if (bw != null) {
                try {
                    bw.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    }

    public static void mkFile(String filePath) {
    }

    public static void main(String[] args) {
        Type0TextEditor.Config();
        String filePath = "hdfs://localhost:9000/user/test/0.txt";
        String content = "";
        Scanner ipt = new Scanner(System.in);
        String input = "";
        String inputPart = "";
        int operation = -1;
        boolean noExit = true;
        boolean commandFlag = false;
        boolean strFlag = false;
        while (noExit) {
            if (ipt.hasNextLine()) {
                input = ipt.nextLine() + " ";
            }
            inputPart = "";
            operation = -1;
            commandFlag = false;
            strFlag = false;
            filePath = "";
            content = "";
            // 输入解析
            for (int i = 0; i < input.length(); i++) {
                if (input.charAt(i) == '
') {
                    continue;
                }
                if (!strFlag) {
                    if (input.charAt(i) != '"') {
                        if (input.charAt(i) != ' ') {
                            inputPart = inputPart + input.charAt(i);
                        } else if (input.charAt(i) == ' ') {
                            if (!inputPart.equals("")) {
                                if (inputPart.equals("open") && operation == -1) {
                                    operation = 0;
                                } else if (inputPart.equals("new") && operation == -1) {
                                    operation = 1;
                                } else if (inputPart.equals("insert") && operation == -1) {
                                    operation = 2;
                                } else if (inputPart.equals("-start") && operation == 2) {
                                    operation = 3;
                                } else if (inputPart.equals("-end") && operation == 2) {
                                    operation = 4;
                                } else if (inputPart.equals("exit") && operation == -1) {
                                    operation = 5;
                                } else {
                                    System.out.println("Syntax error![CODE:1]");
                                    operation = -1;
                                    break;
                                }
                                inputPart = "";
                            }
                        }
                    } else {// 遇到'"'
                        if (inputPart.equals("")) {
                            strFlag = true;
                        } else {
                            System.out.println("Syntax error![CODE:2]");
                            operation = -1;
                            break;
                        }
                    }
                } else {// 字符串
                    if (commandFlag) {
                        if (input.charAt(i) == '\') {
                            inputPart = inputPart + "\";
                        } else if (input.charAt(i) == '"') {
                            inputPart = inputPart + """;
                        } else if (input.charAt(i) == 'n') {
                            inputPart = inputPart + "
";
                        } else if (input.charAt(i) == 't') {
                            inputPart = inputPart + "	";
                        } else {
                            inputPart = inputPart + "\" + input.charAt(i);
                        }
                        commandFlag = false;
                    } else {
                        if (input.charAt(i) == '\') {
                            commandFlag = true;
                        } else if (input.charAt(i) == '"') {
                            if (operation == 0 || operation == 1) {
                                if (filePath.equals("")) {
                                    filePath = inputPart;
                                    inputPart = "";
                                } else {
                                    System.out.println("Syntax error![CODE:3]");
                                    operation = -1;
                                    break;
                                }
                            } else if (operation == 2 || operation == 3 || operation == 4) {
                                if (filePath.equals("")) {
                                    filePath = inputPart;
                                    inputPart = "";
                                } else if (content.equals("")) {
                                    content = inputPart;
                                    inputPart = "";
                                } else {
                                    System.out.println("Syntax error![CODE:4]");
                                    operation = -1;
                                    break;
                                }
                            } else {
                                System.out.println("Syntax error![CODE:5]");
                                operation = -1;
                                break;
                            }
                            inputPart = "";
                            strFlag = false;
                        } else {
                            inputPart = inputPart + input.charAt(i);
                        }
                    }
                }
            }
            // 解析完成
            System.out.println("[]" + filePath + "||" + content + "[]");
            if (operation == 0 && !filePath.equals("")) {
                if (hasFile(filePath)) {
                    content = readFile(filePath);
                    System.out.println("[OPEN]File "" + filePath + "" is Below");
                    System.out.println(content);
                } else {
                    System.out.println("[OPEN]No such file on " + filePath);
                }
            } else if (operation == 1 && !filePath.equals("")) {
                writeFile("", filePath);
                System.out.println("[NEW]Created File on:" + filePath);
            } else if ((operation == 2 || operation == 4) && !filePath.equals("") && !content.equals("")) {
                if (hasFile(filePath)) {
                    writeFile(readFile(filePath) + content, filePath);
                    System.out.println("[INSERT]Inserted content to end of " + filePath);
                } else {
                    System.out.println("[INSERT]No such file on " + filePath);
                }
            } else if (operation == 3 && !filePath.equals("") && !content.equals("")) {
                if (hasFile(filePath)) {
                    writeFile(content + readFile(filePath), filePath);
                    System.out.println("[INSERT]Inserted content to start of " + filePath);
                } else {
                    System.out.println("[INSERT]No such file on " + filePath);
                }
            } else if (operation == 5) {
                System.out.println("[EXIT]Exited Program");
                break;
            } else {
                if (operation == 0) {
                    System.out.println("[OPEN]Usage:
open <FilePath>");
                } else if (operation == 1) {
                    System.out.println("[NEW]Usage:
new <FilePath>");
                } else if (operation == 2 || operation == 3 || operation == 4) {
                    System.out.println("[INSERT]Usage:
insert [-start|-end] <FilePath> <ContentText>");
                } else {
                }
            }
        }

        ipt.close();
    }
}