1 | package org.greenstone.gatherer.util;
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2 |
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3 |
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4 | import java.io.BufferedReader;
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5 | import java.io.BufferedWriter;
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6 | import java.io.InputStreamReader;
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7 | import java.io.IOException;
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8 | import java.io.OutputStreamWriter;
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9 | import org.greenstone.gatherer.DebugStream;
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10 |
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11 |
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12 | /**
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13 | * This class provides a convenient method of running external programs and viewing/analysing
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14 | * their output. The external programs may be run with or without arguments.
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15 | */
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16 | public class ExternalProgram
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17 | {
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18 | private Process programProcess = null;
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19 |
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20 | private BufferedReader programOut = null;
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21 | private BufferedReader programErr = null;
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22 |
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23 |
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24 | /**
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25 | * Prepares to run a specified external program with the specified arguments.
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26 | *
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27 | * @param programName The name (and path, if necessary) of the program to run.
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28 | * @param programArgs The arguments to provide to the program when run.
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29 | */
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30 | public ExternalProgram(String programName, String programArgs)
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31 | throws IOException
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32 | {
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33 | // Run the program
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34 | programProcess = Runtime.getRuntime().exec(programName + " " + programArgs);
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35 |
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36 | // Grab the program output
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37 | programOut = new BufferedReader(new InputStreamReader(programProcess.getInputStream()));
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38 | programErr = new BufferedReader(new InputStreamReader(programProcess.getErrorStream()));
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39 |
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40 | }
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41 |
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42 |
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43 |
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44 | /**
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45 | */
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46 | public int exitProgram()
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47 | throws IOException
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48 | {
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49 | // Finished, thank you
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50 | //programIn.close();
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51 |
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52 | // Wait for the process to finish
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53 | try {
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54 | programProcess.waitFor();
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55 | }
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56 | catch (InterruptedException ex) {
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57 | throw new Error("Internal Error: Process interrupted.\n" + ex);
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58 | }
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59 |
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60 | // Return the program exit value
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61 | return programProcess.exitValue();
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62 | }
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63 |
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64 |
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65 | /**
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66 | * Returns a single line of output sent by the program to standard output.
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67 | *
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68 | * @return a single line of output sent by the program to standard output.
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69 | */
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70 | public String getLineOfProgramOutput()
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71 | {
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72 | // Read in a line from the program output
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73 | try {
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74 | if (programOut.ready())
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75 | return programOut.readLine();
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76 | else
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77 | return null;
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78 | }
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79 | catch (IOException ex) {
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80 | DebugStream.println("Error: Exception occurred while reading program output.");
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81 | DebugStream.println("Exception: " + ex);
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82 | return null;
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83 | }
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84 | }
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85 |
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86 |
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87 | /**
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88 | * Returns a single line of output sent by the program to standard error.
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89 | *
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90 | * @return a single line of output sent by the program to standard error.
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91 | */
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92 | public String getLineOfProgramError()
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93 | {
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94 | // Read in a line from the program error
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95 | try {
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96 | if (programErr.ready())
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97 | return programErr.readLine();
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98 | else
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99 | return null;
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100 | }
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101 | catch (IOException ex) {
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102 | DebugStream.println("Error: Exception occurred while reading program error.");
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103 | DebugStream.println("Exception: " + ex);
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104 | return null;
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105 | }
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106 | }
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107 | }
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