一、前言

基于spring-web(4.1.4)包的org.springframework.web.bind.ServletRequestUtils工具类对HttpServletRequest获取的传递入参获取request.getParameter进行常见默认数据类型（整型IntParser、长整型LongParser、浮点数类型FloatParser、双精度浮点数、布尔型类型DoubleParser、字符串类型StringParser）的转换，具体代码如下所示

二、源码说明

package org.springframework.web.bind;@b@@b@import javax.servlet.ServletRequest;@b@@b@public abstract class ServletRequestUtils@b@{@b@  private static final IntParser INT_PARSER = new IntParser(null);@b@  private static final LongParser LONG_PARSER = new LongParser(null);@b@  private static final FloatParser FLOAT_PARSER = new FloatParser(null);@b@  private static final DoubleParser DOUBLE_PARSER = new DoubleParser(null);@b@  private static final BooleanParser BOOLEAN_PARSER = new BooleanParser(null);@b@  private static final StringParser STRING_PARSER = new StringParser(null);@b@@b@  public static Integer getIntParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    if (request.getParameter(name) == null)@b@      return null;@b@@b@    return Integer.valueOf(getRequiredIntParameter(request, name));@b@  }@b@@b@  public static int getIntParameter(ServletRequest request, String name, int defaultVal)@b@  {@b@    if (request.getParameter(name) == null)@b@      return defaultVal;@b@    try@b@    {@b@      return getRequiredIntParameter(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return defaultVal;@b@  }@b@@b@  public static int[] getIntParameters(ServletRequest request, String name)@b@  {@b@    try@b@    {@b@      return getRequiredIntParameters(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return new int[0];@b@  }@b@@b@  public static int getRequiredIntParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return INT_PARSER.parseInt(name, request.getParameter(name));@b@  }@b@@b@  public static int[] getRequiredIntParameters(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return INT_PARSER.parseInts(name, request.getParameterValues(name));@b@  }@b@@b@  public static Long getLongParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    if (request.getParameter(name) == null)@b@      return null;@b@@b@    return Long.valueOf(getRequiredLongParameter(request, name));@b@  }@b@@b@  public static long getLongParameter(ServletRequest request, String name, long defaultVal)@b@  {@b@    if (request.getParameter(name) == null)@b@      return defaultVal;@b@    try@b@    {@b@      return getRequiredLongParameter(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return defaultVal;@b@  }@b@@b@  public static long[] getLongParameters(ServletRequest request, String name)@b@  {@b@    try@b@    {@b@      return getRequiredLongParameters(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return new long[0];@b@  }@b@@b@  public static long getRequiredLongParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return LONG_PARSER.parseLong(name, request.getParameter(name));@b@  }@b@@b@  public static long[] getRequiredLongParameters(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return LONG_PARSER.parseLongs(name, request.getParameterValues(name));@b@  }@b@@b@  public static Float getFloatParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    if (request.getParameter(name) == null)@b@      return null;@b@@b@    return Float.valueOf(getRequiredFloatParameter(request, name));@b@  }@b@@b@  public static float getFloatParameter(ServletRequest request, String name, float defaultVal)@b@  {@b@    if (request.getParameter(name) == null)@b@      return defaultVal;@b@    try@b@    {@b@      return getRequiredFloatParameter(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return defaultVal;@b@  }@b@@b@  public static float[] getFloatParameters(ServletRequest request, String name)@b@  {@b@    try@b@    {@b@      return getRequiredFloatParameters(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return new float[0];@b@  }@b@@b@  public static float getRequiredFloatParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return FLOAT_PARSER.parseFloat(name, request.getParameter(name));@b@  }@b@@b@  public static float[] getRequiredFloatParameters(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return FLOAT_PARSER.parseFloats(name, request.getParameterValues(name));@b@  }@b@@b@  public static Double getDoubleParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    if (request.getParameter(name) == null)@b@      return null;@b@@b@    return Double.valueOf(getRequiredDoubleParameter(request, name));@b@  }@b@@b@  public static double getDoubleParameter(ServletRequest request, String name, double defaultVal)@b@  {@b@    if (request.getParameter(name) == null)@b@      return defaultVal;@b@    try@b@    {@b@      return getRequiredDoubleParameter(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return defaultVal;@b@  }@b@@b@  public static double[] getDoubleParameters(ServletRequest request, String name)@b@  {@b@    try@b@    {@b@      return getRequiredDoubleParameters(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return new double[0];@b@  }@b@@b@  public static double getRequiredDoubleParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return DOUBLE_PARSER.parseDouble(name, request.getParameter(name));@b@  }@b@@b@  public static double[] getRequiredDoubleParameters(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return DOUBLE_PARSER.parseDoubles(name, request.getParameterValues(name));@b@  }@b@@b@  public static Boolean getBooleanParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    if (request.getParameter(name) == null)@b@      return null;@b@@b@    return Boolean.valueOf(getRequiredBooleanParameter(request, name));@b@  }@b@@b@  public static boolean getBooleanParameter(ServletRequest request, String name, boolean defaultVal)@b@  {@b@    if (request.getParameter(name) == null)@b@      return defaultVal;@b@    try@b@    {@b@      return getRequiredBooleanParameter(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return defaultVal;@b@  }@b@@b@  public static boolean[] getBooleanParameters(ServletRequest request, String name)@b@  {@b@    try@b@    {@b@      return getRequiredBooleanParameters(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return new boolean[0];@b@  }@b@@b@  public static boolean getRequiredBooleanParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return BOOLEAN_PARSER.parseBoolean(name, request.getParameter(name));@b@  }@b@@b@  public static boolean[] getRequiredBooleanParameters(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return BOOLEAN_PARSER.parseBooleans(name, request.getParameterValues(name));@b@  }@b@@b@  public static String getStringParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    if (request.getParameter(name) == null)@b@      return null;@b@@b@    return getRequiredStringParameter(request, name);@b@  }@b@@b@  public static String getStringParameter(ServletRequest request, String name, String defaultVal)@b@  {@b@    String val = request.getParameter(name);@b@    return ((val != null) ? val : defaultVal);@b@  }@b@@b@  public static String[] getStringParameters(ServletRequest request, String name)@b@  {@b@    try@b@    {@b@      return getRequiredStringParameters(request, name);@b@    } catch (ServletRequestBindingException ex) {@b@    }@b@    return new String[0];@b@  }@b@@b@  public static String getRequiredStringParameter(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return STRING_PARSER.validateRequiredString(name, request.getParameter(name));@b@  }@b@@b@  public static String[] getRequiredStringParameters(ServletRequest request, String name)@b@    throws ServletRequestBindingException@b@  {@b@    return STRING_PARSER.validateRequiredStrings(name, request.getParameterValues(name));@b@  }@b@@b@  private static class StringParser extends ServletRequestUtils.ParameterParser<String>@b@  {@b@    private StringParser()@b@    {@b@      super(null);@b@    }@b@@b@    protected String getType() {@b@      return "string";@b@    }@b@@b@    protected String doParse(String parameter) throws NumberFormatException@b@    {@b@      return parameter;@b@    }@b@@b@    public String validateRequiredString(String name, String value) throws ServletRequestBindingException {@b@      validateRequiredParameter(name, value);@b@      return value;@b@    }@b@@b@    public String[] validateRequiredStrings(String name, String[] values) throws ServletRequestBindingException {@b@      validateRequiredParameter(name, values);@b@      String[] arrayOfString = values; int i = arrayOfString.length; for (int j = 0; j < i; ++j) { String value = arrayOfString[j];@b@        validateRequiredParameter(name, value);@b@      }@b@      return values;@b@    }@b@  }@b@@b@  private static class BooleanParser extends ServletRequestUtils.ParameterParser<Boolean>@b@  {@b@    private BooleanParser()@b@    {@b@      super(null);@b@    }@b@@b@    protected String getType() {@b@      return "boolean";@b@    }@b@@b@    protected Boolean doParse(String parameter) throws NumberFormatException@b@    {@b@      return Boolean.valueOf((parameter.equalsIgnoreCase("true")) || (parameter.equalsIgnoreCase("on")) || @b@        (parameter@b@        .equalsIgnoreCase("yes")) || @b@        (parameter.equals("1")));@b@    }@b@@b@    public boolean parseBoolean(String name, String parameter) throws ServletRequestBindingException {@b@      return ((Boolean)parse(name, parameter)).booleanValue();@b@    }@b@@b@    public boolean[] parseBooleans(String name, String[] values) throws ServletRequestBindingException {@b@      validateRequiredParameter(name, values);@b@      boolean[] parameters = new boolean[values.length];@b@      for (int i = 0; i < values.length; ++i)@b@        parameters[i] = parseBoolean(name, values[i]);@b@@b@      return parameters;@b@    }@b@  }@b@@b@  private static class DoubleParser extends ServletRequestUtils.ParameterParser<Double>@b@  {@b@    private DoubleParser()@b@    {@b@      super(null);@b@    }@b@@b@    protected String getType() {@b@      return "double";@b@    }@b@@b@    protected Double doParse(String parameter) throws NumberFormatException@b@    {@b@      return Double.valueOf(parameter);@b@    }@b@@b@    public double parseDouble(String name, String parameter) throws ServletRequestBindingException {@b@      return ((Double)parse(name, parameter)).doubleValue();@b@    }@b@@b@    public double[] parseDoubles(String name, String[] values) throws ServletRequestBindingException {@b@      validateRequiredParameter(name, values);@b@      double[] parameters = new double[values.length];@b@      for (int i = 0; i < values.length; ++i)@b@        parameters[i] = parseDouble(name, values[i]);@b@@b@      return parameters;@b@    }@b@  }@b@@b@  private static class FloatParser extends ServletRequestUtils.ParameterParser<Float>@b@  {@b@    private FloatParser()@b@    {@b@      super(null);@b@    }@b@@b@    protected String getType() {@b@      return "float";@b@    }@b@@b@    protected Float doParse(String parameter) throws NumberFormatException@b@    {@b@      return Float.valueOf(parameter);@b@    }@b@@b@    public float parseFloat(String name, String parameter) throws ServletRequestBindingException {@b@      return ((Float)parse(name, parameter)).floatValue();@b@    }@b@@b@    public float[] parseFloats(String name, String[] values) throws ServletRequestBindingException {@b@      validateRequiredParameter(name, values);@b@      float[] parameters = new float[values.length];@b@      for (int i = 0; i < values.length; ++i)@b@        parameters[i] = parseFloat(name, values[i]);@b@@b@      return parameters;@b@    }@b@  }@b@@b@  private static class LongParser extends ServletRequestUtils.ParameterParser<Long>@b@  {@b@    private LongParser()@b@    {@b@      super(null);@b@    }@b@@b@    protected String getType() {@b@      return "long";@b@    }@b@@b@    protected Long doParse(String parameter) throws NumberFormatException@b@    {@b@      return Long.valueOf(parameter);@b@    }@b@@b@    public long parseLong(String name, String parameter) throws ServletRequestBindingException {@b@      return ((Long)parse(name, parameter)).longValue();@b@    }@b@@b@    public long[] parseLongs(String name, String[] values) throws ServletRequestBindingException {@b@      validateRequiredParameter(name, values);@b@      long[] parameters = new long[values.length];@b@      for (int i = 0; i < values.length; ++i)@b@        parameters[i] = parseLong(name, values[i]);@b@@b@      return parameters;@b@    }@b@  }@b@@b@  private static class IntParser extends ServletRequestUtils.ParameterParser<Integer>@b@  {@b@    private IntParser()@b@    {@b@      super(null);@b@    }@b@@b@    protected String getType() {@b@      return "int";@b@    }@b@@b@    protected Integer doParse(String s) throws NumberFormatException@b@    {@b@      return Integer.valueOf(s);@b@    }@b@@b@    public int parseInt(String name, String parameter) throws ServletRequestBindingException {@b@      return ((Integer)parse(name, parameter)).intValue();@b@    }@b@@b@    public int[] parseInts(String name, String[] values) throws ServletRequestBindingException {@b@      validateRequiredParameter(name, values);@b@      int[] parameters = new int[values.length];@b@      for (int i = 0; i < values.length; ++i)@b@        parameters[i] = parseInt(name, values[i]);@b@@b@      return parameters;@b@    }@b@  }@b@@b@  private static abstract class ParameterParser<T>@b@  {@b@    protected final T parse(String name, String parameter)@b@      throws ServletRequestBindingException@b@    {@b@      validateRequiredParameter(name, parameter);@b@      try {@b@        return doParse(parameter);@b@      }@b@      catch (NumberFormatException ex)@b@      {@b@        throw new ServletRequestBindingException("Required " + @b@          getType() + " parameter '" + name + "' with value of '" + parameter + "' is not a valid number", ex);@b@      }@b@    }@b@@b@    protected final void validateRequiredParameter(String name, Object parameter)@b@      throws ServletRequestBindingException@b@    {@b@      if (parameter == null)@b@        throw new MissingServletRequestParameterException(name, getType());@b@    }@b@@b@    protected abstract String getType();@b@@b@    protected abstract T doParse(String paramString)@b@      throws NumberFormatException;@b@  }@b@}