APN(default、mms、supl、dun、hipri接入点类型的区别)

设置APN上网时，大家可能经常遇到这个问题：
为什么有时要填写default有时要填写supl，而彩信又偏偏要mms？
这个问题留到最后，让我们看看每个接入点类型的含义：
英文原文来自于Google Android Developers
原文连接:http://developer.android.com/reference/android/net/ConnectivityManager.html
我尽量用通俗易懂的语言来解释每个类型的含义，若您是开发者，请尽量阅读英文原文。

1、default
‍默认网络连接，当激活时所有数据传输都使用该连接，不能与其他网络连接同时使用

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<span style="color: rgb(8, 0, 0); font-style: italic; font-weight: bold;">/** * The Default Mobile data connection. When active, all data traffic * will use this connection by default. Should not coexist with other * default connections. */</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">public</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">static</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">final</span> <span style="color: rgb(0, 102, 0); font-weight: bold;">int</span> TYPE_MOBILE <span style="color: rgb(51, 153, 51);">=</span> <span style="color: rgb(204, 102, 204);">0</span><span style="color: rgb(51, 153, 51);">;</span> <span style="color:#880000;font-style: italic; font-weight: bold;">/** * The Default Mobile data connection. When active, all data traffic * will use this connection by default. Should not coexist with other * default connections. */</span> <span style="color:#000000;font-weight: bold;">public</span> <span style="color:#000000;font-weight: bold;">static</span> <span style="color:#000000;font-weight: bold;">final</span> <span style="color:#0660;font-weight: bold;">int</span> TYPE_MOBILE <span style="color:#339933;">=</span> <span style="color:#cc66cc;">0</span><span style="color:#339933;">;</span>

适用场合：绝大部分正常上网时可以使用
2、mms
彩信专用连接，此连接与default类似，用于与载体的多媒体信息服务器对话的应用程序，此连接能与default连接同时使用

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<span style="color: rgb(8, 0, 0); font-style: italic; font-weight: bold;">/** * An MMS-specific Mobile data connection. This connection may be the * same as TYPE_MOBILE but it may be different. This is used * by applications needing to talk to the carrier's Multimedia Messaging * Service servers. It may coexist with default data connections. */</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">public</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">static</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">final</span> <span style="color: rgb(0, 102, 0); font-weight: bold;">int</span> TYPE_MOBILE_MMS <span style="color: rgb(51, 153, 51);">=</span> <span style="color: rgb(204, 102, 204);">2</span><span style="color: rgb(51, 153, 51);">;</span> <span style="color:#880000;font-style: italic; font-weight: bold;">/** * An MMS-specific Mobile data connection. This connection may be the * same as TYPE_MOBILE but it may be different. This is used * by applications needing to talk to the carrier's Multimedia Messaging * Service servers. It may coexist with default data connections. */</span> <span style="color:#000000;font-weight: bold;">public</span> <span style="color:#000000;font-weight: bold;">static</span> <span style="color:#000000;font-weight: bold;">final</span> <span style="color:#0660;font-weight: bold;">int</span> TYPE_MOBILE_MMS <span style="color:#339933;">=</span> <span style="color:#cc66cc;">2</span><span style="color:#339933;">;</span>

适用场合：使用彩信服务时，必须有mms类型的接入点，不必选中，应用程序会自动使用此接入点
3、supl
是Secure User Plane Location“安全用户面定位”的简写，此连接与default类似，用于帮助定位设备与载体的安全用户面定位服务器对话的应用程序，此连接能与default连接同时使用

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<span style="color: rgb(8, 0, 0); font-style: italic; font-weight: bold;">/** * A SUPL-specific Mobile data connection. This connection may be the * same as {@link #TYPEMOBILE} but it may be different. This is used * by applications needing to talk to the carrier's Secure User Plane * Location servers for help locating the device. It may coexist with * default data connections. * {@hide} */</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">public</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">static</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">final</span> <span style="color: rgb(0, 102, 0); font-weight: bold;">int</span> TYPE_MOBILE_SUPL <span style="color: rgb(51, 153, 51);">=</span> <span style="color: rgb(204, 102, 204);">3</span><span style="color: rgb(51, 153, 51);">;</span> <span style="color:#880000;font-style: italic; font-weight: bold;">/** * A SUPL-specific Mobile data connection. This connection may be the * same as {@link #TYPEMOBILE} but it may be different. This is used * by applications needing to talk to the carrier's Secure User Plane * Location servers for help locating the device. It may coexist with * default data connections. * {@hide} */</span> <span style="color:#000000;font-weight: bold;">public</span> <span style="color:#000000;font-weight: bold;">static</span> <span style="color:#000000;font-weight: bold;">final</span> <span style="color:#0660;font-weight: bold;">int</span> TYPE_MOBILE_SUPL <span style="color:#339933;">=</span> <span style="color:#cc66cc;">3</span><span style="color:#339933;">;</span>

适用场合:需要自动切换wap与net接入点的、需要把手机当临时AP的
对SUPL技术感兴趣的朋友，不妨看下以下文章
SUPL技术(一)http://blog.sina.com.cn/s/blog_537f4a11010008tw.html
SUPL技术(二)http://blog.sina.com.cn/s/blog_537f4a11010008uf.html
SUPL技术(三)http://blog.sina.com.cn/s/blog_537f4a11010008ws.html
SUPL技术(四)http://blog.sina.com.cn/s/blog_537f4a11010008yf.html
4、dun
Dial Up Networking拨号网络的简称，此连接与default连接类似，用于执行一个拨号网络网桥，使载体能知道拨号网络流量的应用程序，此连接能与default连接同时使用

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<span style="color: rgb(8, 0, 0); font-style: italic; font-weight: bold;">/** * A DUN-specific Mobile data connection. This connection may be the * same as {@link #TYPEMOBILE} but it may be different. This is used * by applicaitons performing a Dial Up Networking bridge so that * the carrier is aware of DUN traffic. It may coexist with default data * connections. */</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">public</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">static</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">final</span> <span style="color: rgb(0, 102, 0); font-weight: bold;">int</span> TYPE_MOBILE_DUN <span style="color: rgb(51, 153, 51);">=</span> <span style="color: rgb(204, 102, 204);">4</span><span style="color: rgb(51, 153, 51);">;</span> <span style="color:#880000;font-style: italic; font-weight: bold;">/** * A DUN-specific Mobile data connection. This connection may be the * same as {@link #TYPEMOBILE} but it may be different. This is used * by applicaitons performing a Dial Up Networking bridge so that * the carrier is aware of DUN traffic. It may coexist with default data * connections. */</span> <span style="color:#000000;font-weight: bold;">public</span> <span style="color:#000000;font-weight: bold;">static</span> <span style="color:#000000;font-weight: bold;">final</span> <span style="color:#0660;font-weight: bold;">int</span> TYPE_MOBILE_DUN <span style="color:#339933;">=</span> <span style="color:#cc66cc;">4</span><span style="color:#339933;">;</span>

适用场合：需要使用运营商无线热点的，CMCC、ChinaNet等
5、hipri
高优先级网络，与default类似，但路由设置不同。
只有当进程访问移动DNS服务器，并明确要求使用requestRouteToHost(int, int)才会使用此连接
（这个我也不太懂，翻译的应该很有问题….）

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<span style="color: rgb(8, 0, 0); font-style: italic; font-weight: bold;">/** * A High Priority Mobile data connection. This connection is typically * the same as {@link #TYPEMOBILE} but the routing setup is different. * Only requesting processes will have access to the Mobile DNS servers * and only IP's explicitly requested via {@link #requestRouteToHost} * will route over this interface. *{@hide} */</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">public</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">static</span> <span style="color: rgb(0, 0, 0); font-weight: bold;">final</span> <span style="color: rgb(0, 102, 0); font-weight: bold;">int</span> TYPE_MOBILE_HIPRI <span style="color: rgb(51, 153, 51);">=</span> <span style="color: rgb(204, 102, 204);">5</span><span style="color: rgb(51, 153, 51);">;</span> <span style="color:#880000;font-style: italic; font-weight: bold;">/** * A High Priority Mobile data connection. This connection is typically * the same as {@link #TYPEMOBILE} but the routing setup is different. * Only requesting processes will have access to the Mobile DNS servers * and only IP's explicitly requested via {@link #requestRouteToHost} * will route over this interface. *{@hide} */</span> <span style="color:#000000;font-weight: bold;">public</span> <span style="color:#000000;font-weight: bold;">static</span> <span style="color:#000000;font-weight: bold;">final</span> <span style="color:#0660;font-weight: bold;">int</span> TYPE_MOBILE_HIPRI <span style="color:#339933;">=</span> <span style="color:#cc