一、Android应用获取有线网络DNS列表

/*** 获取DNS列表*/

private ListgetDnsList() {

List dnsList = newArrayList();if (this.mIEthernetManager == null) {returndnsList;

}else{try{

IpConfiguration config= this.mIEthernetManager.getConfiguration();

Iterator i$;

InetAddress nameserver;if (config.getIpAssignment() ==IpConfiguration.IpAssignment.STATIC) {int state = this.mIEthernetManager.getState();if (state != 3) {returndnsList;

}

i$=config.getStaticIpConfiguration().dnsServers.iterator();while(i$.hasNext()) {

nameserver=(InetAddress)i$.next();

dnsList.add(nameserver.getHostAddress());

}

}else{if (this.mIConnectivityManager == null) {returndnsList;

}

LinkProperties lp= this.mIConnectivityManager.getLinkPropertiesForType(9);if (lp == null) {returndnsList;

}

i$=lp.getDnsServers().iterator();while(i$.hasNext()) {

nameserver=(InetAddress)i$.next();

dnsList.add(nameserver.getHostAddress());

}

}returndnsList;

}catch (NullPointerException |RemoteException var6) {

var6.printStackTrace();returndnsList;

}

}

}

二、framework层修改DNS列表IPv4/IPv6的优先级

路由器同时支持IPv4和IPv6的情况下，Android系统会优先使用IPv6，DNS信息中可能会显示类似 "fe80:xx:xx"的格式，这就是IPv6的DNS格式。

修改DNS列表，把IPv4放在首位返回：

frameworks\base\core\java\android\net\LinkProperties.java

/*** Returns all the {@linkInetAddress} for DNS servers on this link.

*

*@returnAn umodifiable {@linkList} of {@linkInetAddress} for DNS servers on

* this link.*/

public ListgetDnsServers() {//Sheldon add patch begin//在列表中查找到有IPv4 DNS且不在首位时，将其交换到首位，应用层获取到的列表第一个便是IPv4的DNS

int index = 0;boolean isSortDone = true;for(InetAddress addr : mDnses) {boolean isIpv4 = (addr instanceofInet4Address);if(index==0 && !isIpv4){

isSortDone= false;

}//Log.v(TAG, "Get DNS : " + addr.getHostAddress() + ", isIpv4 : " + isIpv4 + ", index = " + index);

if(!isSortDone &&isIpv4){

Collections.swap(mDnses,0,index);

Log.d(TAG,"Put ipv4 dns first ~");

isSortDone= true;

}

index++;

}//Sheldon add patch end

returnCollections.unmodifiableList(mDnses);

}

另外，如果想默认关闭IPv6只使用IPv4可以进行如下修改：

frameworks\opt\net\ethernet\java\com\android\server\ethernet\EthernetNetworkFactory.java

public voidstartIpManager() {

......

}else{

provisioningConfiguration=mIpManager.buildProvisioningConfiguration()

.withProvisioningTimeoutMs(0)

.withoutIPv6()//默认配置去除IPv6

.build();

}

mIpManager.startProvisioning(provisioningConfiguration);

}