MimeHeaders (Apache Tomcat 7.0.109 API Documentation)

java.lang.Object
- org.apache.tomcat.util.http.MimeHeaders

```
public class MimeHeaders
extends Object
```
Memory-efficient repository for Mime Headers. When the object is recycled, it will keep the allocated headers[] and all the MimeHeaderField - no GC is generated. For input headers it is possible to use the MessageByte for Fields - so no GC will be generated. The only garbage is generated when using the String for header names/values - this can't be avoided when the servlet calls header methods, but is easy to avoid inside tomcat. The goal is to use _only_ MessageByte-based Fields, and reduce to 0 the memory overhead of tomcat. TODO: XXX one-buffer parsing - for http ( other protocols don't need that ) XXX remove unused methods XXX External enumerations, with 0 GC. XXX use HeaderName ID

Author:

dac@eng.sun.com, James Todd [gonzo@eng.sun.com], Costin Manolache, kevin seguin

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`DEFAULT_HEADER_SIZE` Initial size - should be == average number of headers per request XXX make it configurable ( fine-tuning of web-apps )

Constructor Summary

Constructors
Constructor and Description

MimeHeaders()
Creates a new MimeHeaders object using a default buffer size.

Constructors
Constructor and Description
`MimeHeaders()` Creates a new MimeHeaders object using a default buffer size.

Method Summary

Methods
Modifier and Type	Method and Description
`MessageBytes`	`addValue(byte[] b, int startN, int len)` Create a new named header using un-translated byte[].
`MessageBytes`	`addValue(char[] c, int startN, int len)` Create a new named header using translated char[].
`MessageBytes`	`addValue(String name)` Create a new named header , return the MessageBytes container for the new value
`void`	`clear()` Clears all header fields.
`int`	`findHeader(String name, int starting)` Find the index of a header with the given name.
`String`	`getHeader(String name)`
`MessageBytes`	`getName(int n)`
`MessageBytes`	`getUniqueValue(String name)` Finds and returns a unique header field with the given name.
`MessageBytes`	`getValue(int n)`
`MessageBytes`	`getValue(String name)` Finds and returns a header field with the given name.
`Enumeration<String>`	`names()` Returns an enumeration of strings representing the header field names.
`void`	`recycle()` Clears all header fields.
`void`	`removeHeader(int idx)` reset and swap with last header
`void`	`removeHeader(String name)` Removes a header field with the specified name.
`void`	`setLimit(int limit)` Set limit on the number of header fields.
`MessageBytes`	`setValue(String name)` Allow "set" operations, which removes all current values for this header.
`int`	`size()`
`String`	`toString()` EXPENSIVE!!!
`Enumeration<String>`	`values(String name)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - DEFAULT_HEADER_SIZE
```
public static final int DEFAULT_HEADER_SIZE
```
    Initial size - should be == average number of headers per request XXX make it configurable ( fine-tuning of web-apps )
    
    See Also:
    Constant Field Values
- Constructor Detail
  - MimeHeaders
```
public MimeHeaders()
```
    Creates a new MimeHeaders object using a default buffer size.
- Method Detail
  - setLimit
```
public void setLimit(int limit)
```
    Set limit on the number of header fields.
    
    Parameters:
    limit - The new limit
  - recycle
```
public void recycle()
```
    Clears all header fields.
  - clear
```
public void clear()
```
    Clears all header fields.
  - toString
```
public String toString()
```
    EXPENSIVE!!! only for debugging.
    
    Overrides:
    
    toString in class Object
  - size
```
public int size()
```
    Returns:
    the current number of header fields.
  - getName
```
public MessageBytes getName(int n)
```
    Parameters:
    n - The header index
    
    Returns:
    the Nth header name, or null if there is no such header. This may be used to iterate through all header fields.
  - getValue
```
public MessageBytes getValue(int n)
```
    Parameters:
    n - The header index
    
    Returns:
    the Nth header value, or null if there is no such header. This may be used to iterate through all header fields.
  - findHeader
```
public int findHeader(String name,
             int starting)
```
    Find the index of a header with the given name.
    
    Parameters:
    name - The header name
    starting - Index on which to start looking
    
    Returns:
    the header index
  - names
```
public Enumeration<String> names()
```
    Returns an enumeration of strings representing the header field names. Field names may appear multiple times in this enumeration, indicating that multiple fields with that name exist in this header.
    
    Returns:
    the enumeration
  - values
```
public Enumeration<String> values(String name)
```
  - addValue
```
public MessageBytes addValue(String name)
```
    Create a new named header , return the MessageBytes container for the new value
    
    Parameters:
    name - The header name
    
    Returns:
    the message bytes container for the value
  - addValue
```
public MessageBytes addValue(byte[] b,
                    int startN,
                    int len)
```
    Create a new named header using un-translated byte[]. The conversion to chars can be delayed until encoding is known.
    
    Parameters:
    b - The header name bytes
    startN - Offset
    len - Length
    
    Returns:
    the message bytes container for the value
  - addValue
```
public MessageBytes addValue(char[] c,
                    int startN,
                    int len)
```
    Create a new named header using translated char[].
  - setValue
```
public MessageBytes setValue(String name)
```
    Allow "set" operations, which removes all current values for this header.
    
    Parameters:
    name - The header name
    
    Returns:
    the message bytes container for the value
  - getValue
```
public MessageBytes getValue(String name)
```
    Finds and returns a header field with the given name. If no such field exists, null is returned. If more than one such field is in the header, an arbitrary one is returned.
    
    Parameters:
    name - The header name
    
    Returns:
    the value
  - getUniqueValue
```
public MessageBytes getUniqueValue(String name)
```
    Finds and returns a unique header field with the given name. If no such field exists, null is returned. If the specified header field is not unique then an IllegalArgumentException is thrown.
    
    Parameters:
    name - The header name
    
    Returns:
    the value if unique
    
    Throws:
    
    IllegalArgumentException - if the header has multiple values
  - getHeader
```
public String getHeader(String name)
```
  - removeHeader
```
public void removeHeader(String name)
```
    Removes a header field with the specified name. Does nothing if such a field could not be found.
    
    Parameters:
    name - the name of the header field to be removed
  - removeHeader
```
public void removeHeader(int idx)
```
    reset and swap with last header
    
    Parameters:
    idx - the index of the header to remove.

Class MimeHeaders

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_HEADER_SIZE

Constructor Detail

MimeHeaders

Method Detail

setLimit

recycle

clear

toString

size

getName

getValue

findHeader

names

values

addValue

addValue

addValue

setValue

getValue

getUniqueValue

getHeader

removeHeader

removeHeader